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Cell (Biology) - Lecture 1
A cell is capable of independent existence and can carry out all the functions which are necessary for a living being. A cell carries out nutrition, respiration, excretion, transportation and reproduction, the way an individual organism does. Unicellular organisms are capable of independent existence which shows a cell's capability to exist independently. Due to this, a cell is called the functional unit of life.
All living beings are composed of the basic unit of life, i.e. cell. So, cell is called the structural unit of life. If you combine both the aspects, i.e. functional unit and structural unit, you can say that a cell is the fundamental unit of life.
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28min
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Nutrition (Biology) - Lecture 2
All the living organisms need energy to perform various life processes. They get this energy from food. Food is a kind of fuel which provides energy to all the living organisms. Food is an organic substance.
Nutrient: A nutrient can be defined as a substance which an organism obtains from its surroundings and uses it as a source of energy or for the biosynthesis of its body constituents. Nutrition is the process of intake of nutrients (like carbohydrates, fats, proteins, minerals, vitamins and water) by an organism as well as the utilization of these nutrients by the organism. Mode of nutrition means method of obtaining food by an organism.
There are mainly two modes of nutrition
1. Autotrophic mode of nutrition
2. Heterotrophic mode of nutrition
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20min
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Transport in Plants (Biology) - Lecture 3
Transportation is a vital process in plants and Animals. Trees transport all the water and nutrients from roots to the other parts of plants for survival from its roots to the tips of the leaves. For the verious metabolic process of plants like photosynthesis, transpiration, guttation raw materials should be transported from root to the leaves. For transport in plants, they need a transport system to move food, water, and minerals around because for them no heart, no blood, and since these plants do not have a circulatory system, transportation makes up for it.
Plants have two transport systems - xylem and phloem.
Xylem tissue transports water and mineral salts from the roots to the other parts of the plant, while phloem transports Carbohydrates, sucrose and amino acids from roots to the leaves and other parts of the plant.
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23min
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Plant Kingdom & Animal Kingdom (Biology) - Lecture 4
Plants are mostly multicellular organisms however, few unicellular organism like algae are also considered as plants. So, we can say term plant is very broad and it includes single celled algae to flower and fruit bearing trees. Plants may be terrestrial or aquatic, plants which are present on the land surface is called terrestrial plant while the plant which floats, submerged or remain suspended in water is called aquatic plants.
The first level of classification among plants depends on whether the plant body has well differentiated, distinct components. The next level of classification is based on whether the differentiated plant body has special tissues for the transport of water and other substances within it. Further classification looks at the ability to bear seeds and whether the seeds are enclosed within fruits.
Animals are multicellular, eukaryotic life forms, characterized by heterotrophic mode of nutrition and inhabit all types of ecosystems including terrestrial, freshwater and marine. They can be further segregated into two groups based on the presence of notochord- chordates and invertebrates. Chordates constitute only 5% of the animal kingdom while the invertebrates claim the remaining majority. Vertebrates form a subphylum under chordates and are characterized by the presence of a vertebral column or backbone. With an exception of sponges, all animal cells are organized into tissues and in majority, the tissues organize to form well-defined organs and organ systems for carrying out essential bodily functions. Most animals are also diploid in nature and reproduce sexually by the formation of gametes.
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33min
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Biological Classification Part 1 (Biology) - Lecture 5
Biological classification is the scientific procedure of arranging organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing the group in a hierarchy of categories.
Importance of classification-
• It is not possible to study every organism. Study of one or two organism of a group gives sufficient information about the essential features of the group.
• It helps in identification of new organism.
• Classification helps in knowing the relationship amongst different groups of organisms.
• The organism of past cannot be studied without a proper system of classification
Five kingdom systems- R.H.Whittaker divided all the organism into five kingdom namely
1. Monera : It includes all the prokaryotes (Eubacteria, Actinomycetes, blue green
algae, Mycoplasma) and Akaryote (virus).
2. Protista : It includes all the unicellular eukaryotes (Protozoans, Dinoflagellates,
Diatoms, Euglenoids, Slime molds).
3. Mycota : It includes true fungi.
4. Plantae : It includes multicellular eukaryotic plants (Algae, Bryophyte,
Pteridophyte, Gymnosperm and Angiosperm).
5. Animalia : It includes multicellular animals.
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24min
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Biological Classification Part 2 (Biology) - Lecture 6
Biological classification is the scientific procedure of arranging organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing the group in a hierarchy of categories.
Importance of classification-
• It is not possible to study every organism. Study of one or two organism of a group gives sufficient information about the essential features of the group.
• It helps in identification of new organism.
• Classification helps in knowing the relationship amongst different groups of organisms.
• The organism of past cannot be studied without a proper system of classification
Five kingdom systems- R.H.Whittaker divided all the organism into five kingdom namely
1. Monera : It includes all the prokaryotes (Eubacteria, Actinomycetes, blue green
algae, Mycoplasma) and Akaryote (virus).
2. Protista : It includes all the unicellular eukaryotes (Protozoans, Dinoflagellates,
Diatoms, Euglenoids, Slime molds).
3. Mycota : It includes true fungi.
4. Plantae : It includes multicellular eukaryotic plants (Algae, Bryophyte,
Pteridophyte, Gymnosperm and Angiosperm).
5. Animalia : It includes multicellular animals.
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17min
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Microorganisms Part 1 (Biology) - Lecture 7
Microorganisms are very small organisms that they cannot be seen with naked eyes. They can be seen under a microscope. These include a number of varieties such as bacteria, viruses, fungi, algae, protozoa, etc. These microbes can be friends or foe to human beings.
Microorganisms are omnipotent i.e; they are present everywhere, in air, in water, in soil and in the body of living organisms.
Some microorganisms can tolerate extreme conditions like a place as hot as boiling water, or a place as cold as ice. Some microorganisms are found alone, while the others are found in colonies.
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17min
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Useful Microorganisms Part 2 (Biology) - Lecture 8
Microorganisms are very small organisms that they cannot be seen with naked eyes. They can be seen under a microscope. These include a number of varieties such as bacteria, viruses, fungi, algae, protozoa, etc. These microbes can be friends or foe to human beings.
Microorganisms are omnipotent i.e; they are present everywhere, in air, in water, in soil and in the body of living organisms.
Some microorganisms can tolerate extreme conditions like a place as hot as boiling water, or a place as cold as ice. Some microorganisms are found alone, while the others are found in colonies.
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14min
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Microorganisms MCQ's Part 3 (Biology) - Lecture 9
Microorganisms are very small organisms that they cannot be seen with naked eyes. They can be seen under a microscope. These include a number of varieties such as bacteria, viruses, fungi, algae, protozoa, etc. These microbes can be friends or foe to human beings.
Microorganisms are omnipotent i.e; they are present everywhere, in air, in water, in soil and in the body of living organisms.
Some microorganisms can tolerate extreme conditions like a place as hot as boiling water, or a place as cold as ice. Some microorganisms are found alone, while the others are found in colonies.
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10min
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Digestion in Humans Part 1 (Biology) - Lecture 10
The food that we eat is to be digested by our body for deriving nutrients from it. Digestion means breaking down of food into simpler substances in the presence of oxygen to release energy. It is a complex process involving following steps , Ingestion, Digestion, Absorption, Assimilation, Egestion.
The parts of digestive tract are:
• Mouth and buccal cavity
• Food pipe/Oesophagus
• Stomach
• Small intestine
• Large intestine
• Rectum
• Anus
There are some associated glands that secrete enzymes which help in digestion of food. These include:
• Salivary glands
• Liver
• Pancreas
The digestive tract and the associated glands together constitute digestive system.
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17min
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Digestion in Humans Part 2 (Biology) - Lecture 11
The food that we eat is to be digested by our body for deriving nutrients from it. Digestion means breaking down of food into simpler substances in the presence of oxygen to release energy. It is a complex process involving following steps , Ingestion, Digestion, Absorption, Assimilation, Egestion.
The parts of digestive tract are:
• Mouth and buccal cavity
• Food pipe/Oesophagus
• Stomach
• Small intestine
• Large intestine
• Rectum
• Anus
There are some associated glands that secrete enzymes which help in digestion of food. These include:
• Salivary glands
• Liver
• Pancreas
The digestive tract and the associated glands together constitute digestive system.
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10min
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Respiration in Humans (Biology) - Lecture 12
The respiratory system includes some tissues and organs that help you breathe. It includes parts like nasal air passage, lungs , alveoli, bronchioles and blood vessels. The muscles that power your lungs are also part of the respiratory system. These all parts work together to transport oxygen throughout the body and clean waste gases like carbon dioxide. The oxygen inhaled is used for the breakdown of food to release energy.
FUNCTION
• helps you to smell and taste
• Warms air to match your body temperature and moisturizes it to the humidity level your body needs.
• Transports oxygen to all cells of your body to release energy
• Removes waste gases like carbon dioxide from the body
• Protects your air passage from harmful particles of dust and microorganisms
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18min
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Excretory System (Biology) - Lecture 13
In humans, the excretory system removes nitrogenous waste along with other metabolic wastes from the body. It consists of few parts, viz. a pair of kidneys, renal arteries and veins, ureters, urinary bladder and urethra. The overall structure of the system is briefly discussed below.
1. The kidneys are bean-shaped organs. These are located on each side of the vertebral column. It performs the filtration blood to produce excretory fluid or urine. The structural and functional unit of the kidney is nephron. A nephron consists of: Bowman’s capsule, glomerulus, proximal tubule, Henle’s loop, distal tubule and collecting duct.
2. Renal arteries carry blood (to be filtered) to the kidneys from heart and renal veins carry filtered blood from kidneys to the inferior vena cava.
3. The kidneys open into the ureters at renal hilum. Ureters are tubes, each of which attach to a kidney and carries urine from kidneys to the urinary bladder.
4. Ureters open into the urinary bladder which is a muscular sac. These urine is stored temporarily. When filled, it contracts and passes the urine to the urethra.
5. A thin, fibro-muscular tube called urethra carries the urine from urethra to the exterior.
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20min
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Controls and Coordination (Biology) - Lecture 14
Control is defined as the power of restraining and regulating by which a process can be started, regulated in pace to speed up or slow down or stop completely.
Coordination can be defined as the working together of the different systems of an organism in order to produce an appropriate reaction to stimuli.
Control and coordination are brought about by the nervous system and the chemical control and coordination occurs with the help of endocrine systems. It regulates all the systems of the body to ensure proper coordination and efficient functioning of an organism.
They are important for an organism to adapt to the changes and perform important functions like metabolism, homeostasis, etc. It also helps in responding to stimuli that help in the fight, or flight responses.
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27min
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Circulatory System (Biology) - Lecture 15
The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.
Circulatory system, system that transports nutrients, respiratory gases, and metabolic products throughout a living organism, permitting integration among the various tissues. The process of circulation includes the intake of metabolic materials, the conveyance of these materials throughout the organism, and the return of harmful by-products to the environment.
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23min
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Reproductive System (Biology) - Lecture 16
Reproduction is essential for species survival. Asexual reproduction involves only one parent, occurs only in lower organisms like Amoeba, yeast, Hydra, etc. Sexual reproduction involves fertilisation or fusion of gametes from males and females. Fertilisation may be external or internal. The sexual reproduction in human beings is a complex process. Both male and female individuals attain maturity by going through a adolescent phase.
Male Reproductive System:
Male reproductive system comprises of- a pair of testis, glands, accessory ducts, and male genitalia.
1. Testis is the site where male gametes or germ cells are produced. They are located outside the abdominal cavity in a sac-like structure known as scrotum. This is to maintain lower temperature required for the formation of sperm. Testes produce male hormone called testosterone. 2. Vas deferens is a duct that transport sperm to urethra, which is a common passage for both urine and sperm ejaculation.
3. Prostate glands and seminal vesicles are also found in males to nourish and for easy transport of sperm in the female genital tract.
Female reproductive system consists of
1. Ovaries produce female cell, ovum. Also secrete hormones oestrogen and progesterone.
2. Fallopian tube facilitates smooth passage of fertilised egg to uterus
3. Uterus a muscular bag, where foetus is established and develops fully into a baby,
4. Cervix and vagina.
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18min
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Motion Part 1 (Physics) - Lecture 1
u Motion : An object which changes its position with respect to a fixed point is said to be in motion.
u Motion is a relative term : An object at rest with respect to one object may also be in motion with respect to another object.
u Reference point : A fixed point with respect to which an object changes its position is known as a reference point.
u Distance : The length of actual path between the initial position and the final position of a moving object or body is known as distance travelled by the particle.
u Displacement : The shortest distance between the initial and final positions of a moving object or body in a direction from initial to the final position of the particle is known as displacement of the particle.
u Units of distance and displacement : SI unit of distance and displacement is metre (m).
u Distance travelled by a body is always positive.
u Displacement of body may be positive, negative or zero.
u Ratio of the magnitude of displacement and the distance is equal to less than 1.
u Uniform Motion : The motion of a body is said to be uniform if (i) it moves along a straight line and (ii) it covers equal distance in equal intervals of time, how-so-ever, small these intervals may be.
u Non-uniform motion : The motion of a body is said to be non-uniform if it covers unequal distance in equal intervals of time.
u Speed : The distance travelled by a body in unit time is known as the speed of the body. That is
u Unit of speed : SI unit of speed is ms–1.
u Uniform speed : If a moving body covers equal distances in equal intervals of time, the speed of the body is uniform.
u Non-Uniform speed : If a moving body covers unequal distances in equal intervals of time, the speed of the body is non-uniform.
u Average speed : The total distance travelled by a body during non-uniform motion divided by the time taken to travel this distance is called average speed.
i.e. Average speed =
u Velocity : The displacement of the body per unit time is known as the velocity of the body. That is,
u Unit of velocity : SI unit of velocity is ms–1.
u Uniform velocity : Velocity of a body is said to be uniform velocity if it covers equal displacements in equal intervals of time.
u Non-uniform velocity : Velocity of a body is said to be non-uniform if it covers unequal displacement in equal intervals of time.
u
u Speed is a scalar quantity, whereas velocity is a vector quantity.
u Speed of a body is always positive.
u Velocity of body can be positive as well as negative.
u Acceleration : Acceleration of a body is defined as the change in velocity per unit time.
i.e.
u Positive acceleration : When the velocity of a body increases with time, acceleration of body is said to be positive acceleration.
Or When the change in velocity (Dv) of a body takes place in the direction of the motion of the body, then the acceleration of the body positive.
u Negative acceleration or retardation or deceleration : If the velocity of the body decreases with time, then acceleration of body is negative acceleration of retardation.
Or When the change in velocity (Dv) of a body takes place in a direction opposite to the direction of motion of the body, then the acceleration of the body is negative.
u S.I. unitof acceleration is m/s2
u
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23min
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Motion Part 2 (Physics) - Lecture 2
u Motion : An object which changes its position with respect to a fixed point is said to be in motion.
u Motion is a relative term : An object at rest with respect to one object may also be in motion with respect to another object.
u Reference point : A fixed point with respect to which an object changes its position is known as a reference point.
u Distance : The length of actual path between the initial position and the final position of a moving object or body is known as distance travelled by the particle.
u Displacement : The shortest distance between the initial and final positions of a moving object or body in a direction from initial to the final position of the particle is known as displacement of the particle.
u Units of distance and displacement : SI unit of distance and displacement is metre (m).
u Distance travelled by a body is always positive.
u Displacement of body may be positive, negative or zero.
u Ratio of the magnitude of displacement and the distance is equal to less than 1.
u Uniform Motion : The motion of a body is said to be uniform if (i) it moves along a straight line and (ii) it covers equal distance in equal intervals of time, how-so-ever, small these intervals may be.
u Non-uniform motion : The motion of a body is said to be non-uniform if it covers unequal distance in equal intervals of time.
u Speed : The distance travelled by a body in unit time is known as the speed of the body. That is
u Unit of speed : SI unit of speed is ms–1.
u Uniform speed : If a moving body covers equal distances in equal intervals of time, the speed of the body is uniform.
u Non-Uniform speed : If a moving body covers unequal distances in equal intervals of time, the speed of the body is non-uniform.
u Average speed : The total distance travelled by a body during non-uniform motion divided by the time taken to travel this distance is called average speed.
i.e. Average speed =
u Velocity : The displacement of the body per unit time is known as the velocity of the body. That is,
u Unit of velocity : SI unit of velocity is ms–1.
u Uniform velocity : Velocity of a body is said to be uniform velocity if it covers equal displacements in equal intervals of time.
u Non-uniform velocity : Velocity of a body is said to be non-uniform if it covers unequal displacement in equal intervals of time.
u
u Speed is a scalar quantity, whereas velocity is a vector quantity.
u Speed of a body is always positive.
u Velocity of body can be positive as well as negative.
u Acceleration : Acceleration of a body is defined as the change in velocity per unit time.
i.e.
u Positive acceleration : When the velocity of a body increases with time, acceleration of body is said to be positive acceleration.
Or When the change in velocity (Dv) of a body takes place in the direction of the motion of the body, then the acceleration of the body positive.
u Negative acceleration or retardation or deceleration : If the velocity of the body decreases with time, then acceleration of body is negative acceleration of retardation.
Or When the change in velocity (Dv) of a body takes place in a direction opposite to the direction of motion of the body, then the acceleration of the body is negative.
u S.I. unitof acceleration is m/s2
u
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22min
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Motion Part 3 (Physics) - Lecture 3
u Motion : An object which changes its position with respect to a fixed point is said to be in motion.
u Motion is a relative term : An object at rest with respect to one object may also be in motion with respect to another object.
u Reference point : A fixed point with respect to which an object changes its position is known as a reference point.
u Distance : The length of actual path between the initial position and the final position of a moving object or body is known as distance travelled by the particle.
u Displacement : The shortest distance between the initial and final positions of a moving object or body in a direction from initial to the final position of the particle is known as displacement of the particle.
u Units of distance and displacement : SI unit of distance and displacement is metre (m).
u Distance travelled by a body is always positive.
u Displacement of body may be positive, negative or zero.
u Ratio of the magnitude of displacement and the distance is equal to less than 1.
u Uniform Motion : The motion of a body is said to be uniform if (i) it moves along a straight line and (ii) it covers equal distance in equal intervals of time, how-so-ever, small these intervals may be.
u Non-uniform motion : The motion of a body is said to be non-uniform if it covers unequal distance in equal intervals of time.
u Speed : The distance travelled by a body in unit time is known as the speed of the body. That is
u Unit of speed : SI unit of speed is ms–1.
u Uniform speed : If a moving body covers equal distances in equal intervals of time, the speed of the body is uniform.
u Non-Uniform speed : If a moving body covers unequal distances in equal intervals of time, the speed of the body is non-uniform.
u Average speed : The total distance travelled by a body during non-uniform motion divided by the time taken to travel this distance is called average speed.
i.e. Average speed =
u Velocity : The displacement of the body per unit time is known as the velocity of the body. That is,
u Unit of velocity : SI unit of velocity is ms–1.
u Uniform velocity : Velocity of a body is said to be uniform velocity if it covers equal displacements in equal intervals of time.
u Non-uniform velocity : Velocity of a body is said to be non-uniform if it covers unequal displacement in equal intervals of time.
u
u Speed is a scalar quantity, whereas velocity is a vector quantity.
u Speed of a body is always positive.
u Velocity of body can be positive as well as negative.
u Acceleration : Acceleration of a body is defined as the change in velocity per unit time.
i.e.
u Positive acceleration : When the velocity of a body increases with time, acceleration of body is said to be positive acceleration.
Or When the change in velocity (Dv) of a body takes place in the direction of the motion of the body, then the acceleration of the body positive.
u Negative acceleration or retardation or deceleration : If the velocity of the body decreases with time, then acceleration of body is negative acceleration of retardation.
Or When the change in velocity (Dv) of a body takes place in a direction opposite to the direction of motion of the body, then the acceleration of the body is negative.
u S.I. unitof acceleration is m/s2
u
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18min
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Motion Numerical Part 4 (Physics) - Lecture 4
u Motion : An object which changes its position with respect to a fixed point is said to be in motion.
u Motion is a relative term : An object at rest with respect to one object may also be in motion with respect to another object.
u Reference point : A fixed point with respect to which an object changes its position is known as a reference point.
u Distance : The length of actual path between the initial position and the final position of a moving object or body is known as distance travelled by the particle.
u Displacement : The shortest distance between the initial and final positions of a moving object or body in a direction from initial to the final position of the particle is known as displacement of the particle.
u Units of distance and displacement : SI unit of distance and displacement is metre (m).
u Distance travelled by a body is always positive.
u Displacement of body may be positive, negative or zero.
u Ratio of the magnitude of displacement and the distance is equal to less than 1.
u Uniform Motion : The motion of a body is said to be uniform if (i) it moves along a straight line and (ii) it covers equal distance in equal intervals of time, how-so-ever, small these intervals may be.
u Non-uniform motion : The motion of a body is said to be non-uniform if it covers unequal distance in equal intervals of time.
u Speed : The distance travelled by a body in unit time is known as the speed of the body. That is
u Unit of speed : SI unit of speed is ms–1.
u Uniform speed : If a moving body covers equal distances in equal intervals of time, the speed of the body is uniform.
u Non-Uniform speed : If a moving body covers unequal distances in equal intervals of time, the speed of the body is non-uniform.
u Average speed : The total distance travelled by a body during non-uniform motion divided by the time taken to travel this distance is called average speed.
i.e. Average speed =
u Velocity : The displacement of the body per unit time is known as the velocity of the body. That is,
u Unit of velocity : SI unit of velocity is ms–1.
u Uniform velocity : Velocity of a body is said to be uniform velocity if it covers equal displacements in equal intervals of time.
u Non-uniform velocity : Velocity of a body is said to be non-uniform if it covers unequal displacement in equal intervals of time.
u
u Speed is a scalar quantity, whereas velocity is a vector quantity.
u Speed of a body is always positive.
u Velocity of body can be positive as well as negative.
u Acceleration : Acceleration of a body is defined as the change in velocity per unit time.
i.e.
u Positive acceleration : When the velocity of a body increases with time, acceleration of body is said to be positive acceleration.
Or When the change in velocity (Dv) of a body takes place in the direction of the motion of the body, then the acceleration of the body positive.
u Negative acceleration or retardation or deceleration : If the velocity of the body decreases with time, then acceleration of body is negative acceleration of retardation.
Or When the change in velocity (Dv) of a body takes place in a direction opposite to the direction of motion of the body, then the acceleration of the body is negative.
u S.I. unitof acceleration is m/s2
u
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24min
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Newton Law of Motion Part 1 (Physics) - Lecture 5
Force :
Force is that cause which produces acceleration in the body on which it acts.
A force or a set of forces can (a) change the speed of the body, (b) change the direction of motion of the body, and (c) change the shape of the body.
If a single force acting on a body produces the same acceleration as produced by a number of forces, this single force is called the resultant or net of the individual forces.
The SI unit of force is the newton, denoted by the symbol (N).
Balanced and unbalanced forces :
If a set of forces acting on a body produces no acceleration in it, the forces are called balanced. If it produces a non zero acceleration, the forces are said to be unbalanced.
Some common forces :
Friction is a force exerted parallel to two surfaces in contact. The effect of friction is to oppose slipping of the two surfaces against each other.
A stretched spring pulls the bodies connected to its ends. A compressed spring pushes the bodies connected to its ends.
A string always pulls an object tied at its end. The magnitude of the force of the pull is called the tension in the string.
The force by which the earth attracts a body is called the weight of the body. It is equal to the mass of the body multiplied by the acceleration due to gravity (W = mg).
Newton’s laws of motion :
First law :A body at rest will remain at rest and a body in motion will remain in uniform motion unless in motion will remain in uniform motion unless acted upon by an unbalanced force.
Second law :The net force acting on a body is proportional to the product of the mass of the body and its acceleration.
Third law :In any interaction between two bodies, the force applied by the first body on the second is equal and opposite to the force applied by the second body on the first.
Definition of newton :
If a force acting on a 1 kg mass produces an acceleration of 1 m/s2 in it, the force is called one newton.
Linear momentum :
The product of the mass of a body and its velocity is called the linear momentum of the body.
The net force on a body is equal to change in its momentum per unit time.
Conservation of linear momentum :
If the net external force acting on a system of particles is zero, the total linear momentum of the system remains constant.0
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27min
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Newton Law of Motion Numerical Part 2 (Physics) - Lecture 6
Force :
Force is that cause which produces acceleration in the body on which it acts.
A force or a set of forces can (a) change the speed of the body, (b) change the direction of motion of the body, and (c) change the shape of the body.
If a single force acting on a body produces the same acceleration as produced by a number of forces, this single force is called the resultant or net of the individual forces.
The SI unit of force is the newton, denoted by the symbol (N).
Balanced and unbalanced forces :
If a set of forces acting on a body produces no acceleration in it, the forces are called balanced. If it produces a non zero acceleration, the forces are said to be unbalanced.
Some common forces :
Friction is a force exerted parallel to two surfaces in contact. The effect of friction is to oppose slipping of the two surfaces against each other.
A stretched spring pulls the bodies connected to its ends. A compressed spring pushes the bodies connected to its ends.
A string always pulls an object tied at its end. The magnitude of the force of the pull is called the tension in the string.
The force by which the earth attracts a body is called the weight of the body. It is equal to the mass of the body multiplied by the acceleration due to gravity (W = mg).
Newton’s laws of motion :
First law :A body at rest will remain at rest and a body in motion will remain in uniform motion unless in motion will remain in uniform motion unless acted upon by an unbalanced force.
Second law :The net force acting on a body is proportional to the product of the mass of the body and its acceleration.
Third law :In any interaction between two bodies, the force applied by the first body on the second is equal and opposite to the force applied by the second body on the first.
Definition of newton :
If a force acting on a 1 kg mass produces an acceleration of 1 m/s2 in it, the force is called one newton.
Linear momentum :
The product of the mass of a body and its velocity is called the linear momentum of the body.
The net force on a body is equal to change in its momentum per unit time.
Conservation of linear momentum :
If the net external force acting on a system of particles is zero, the total linear momentum of the system remains constant.0
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21min
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Work and Energy Part 1 (Physics) - Lecture 7
Force :
Force is that cause which produces acceleration in the body on which it acts.
A force or a set of forces can (a) change the speed of the body, (b) change the direction of motion of the body, and (c) change the shape of the body.
If a single force acting on a body produces the same acceleration as produced by a number of forces, this single force is called the resultant or net of the individual forces.
The SI unit of force is the newton, denoted by the symbol (N).
Balanced and unbalanced forces :
If a set of forces acting on a body produces no acceleration in it, the forces are called balanced. If it produces a non zero acceleration, the forces are said to be unbalanced.
Some common forces :
Friction is a force exerted parallel to two surfaces in contact. The effect of friction is to oppose slipping of the two surfaces against each other.
A stretched spring pulls the bodies connected to its ends. A compressed spring pushes the bodies connected to its ends.
A string always pulls an object tied at its end. The magnitude of the force of the pull is called the tension in the string.
The force by which the earth attracts a body is called the weight of the body. It is equal to the mass of the body multiplied by the acceleration due to gravity (W = mg).
Newton’s laws of motion :
First law :A body at rest will remain at rest and a body in motion will remain in uniform motion unless in motion will remain in uniform motion unless acted upon by an unbalanced force.
Second law :The net force acting on a body is proportional to the product of the mass of the body and its acceleration.
Third law :In any interaction between two bodies, the force applied by the first body on the second is equal and opposite to the force applied by the second body on the first.
Definition of newton :
If a force acting on a 1 kg mass produces an acceleration of 1 m/s2 in it, the force is called one newton.
Linear momentum :
The product of the mass of a body and its velocity is called the linear momentum of the body.
The net force on a body is equal to change in its momentum per unit time.
Conservation of linear momentum :
If the net external force acting on a system of particles is zero, the total linear momentum of the system remains constant.0
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14min
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Work and Energy Power 2 (Physics) - Lecture 8
Force :
Force is that cause which produces acceleration in the body on which it acts.
A force or a set of forces can (a) change the speed of the body, (b) change the direction of motion of the body, and (c) change the shape of the body.
If a single force acting on a body produces the same acceleration as produced by a number of forces, this single force is called the resultant or net of the individual forces.
The SI unit of force is the newton, denoted by the symbol (N).
Balanced and unbalanced forces :
If a set of forces acting on a body produces no acceleration in it, the forces are called balanced. If it produces a non zero acceleration, the forces are said to be unbalanced.
Some common forces :
Friction is a force exerted parallel to two surfaces in contact. The effect of friction is to oppose slipping of the two surfaces against each other.
A stretched spring pulls the bodies connected to its ends. A compressed spring pushes the bodies connected to its ends.
A string always pulls an object tied at its end. The magnitude of the force of the pull is called the tension in the string.
The force by which the earth attracts a body is called the weight of the body. It is equal to the mass of the body multiplied by the acceleration due to gravity (W = mg).
Newton’s laws of motion :
First law :A body at rest will remain at rest and a body in motion will remain in uniform motion unless in motion will remain in uniform motion unless acted upon by an unbalanced force.
Second law :The net force acting on a body is proportional to the product of the mass of the body and its acceleration.
Third law :In any interaction between two bodies, the force applied by the first body on the second is equal and opposite to the force applied by the second body on the first.
Definition of newton :
If a force acting on a 1 kg mass produces an acceleration of 1 m/s2 in it, the force is called one newton.
Linear momentum :
The product of the mass of a body and its velocity is called the linear momentum of the body.
The net force on a body is equal to change in its momentum per unit time.
Conservation of linear momentum :
If the net external force acting on a system of particles is zero, the total linear momentum of the system remains constant.0
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10min
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Work and Energy Power 2 (Physics) - Lecture 8
Force :
Force is that cause which produces acceleration in the body on which it acts.
A force or a set of forces can (a) change the speed of the body, (b) change the direction of motion of the body, and (c) change the shape of the body.
If a single force acting on a body produces the same acceleration as produced by a number of forces, this single force is called the resultant or net of the individual forces.
The SI unit of force is the newton, denoted by the symbol (N).
Balanced and unbalanced forces :
If a set of forces acting on a body produces no acceleration in it, the forces are called balanced. If it produces a non zero acceleration, the forces are said to be unbalanced.
Some common forces :
Friction is a force exerted parallel to two surfaces in contact. The effect of friction is to oppose slipping of the two surfaces against each other.
A stretched spring pulls the bodies connected to its ends. A compressed spring pushes the bodies connected to its ends.
A string always pulls an object tied at its end. The magnitude of the force of the pull is called the tension in the string.
The force by which the earth attracts a body is called the weight of the body. It is equal to the mass of the body multiplied by the acceleration due to gravity (W = mg).
Newton’s laws of motion :
First law :A body at rest will remain at rest and a body in motion will remain in uniform motion unless in motion will remain in uniform motion unless acted upon by an unbalanced force.
Second law :The net force acting on a body is proportional to the product of the mass of the body and its acceleration.
Third law :In any interaction between two bodies, the force applied by the first body on the second is equal and opposite to the force applied by the second body on the first.
Definition of newton :
If a force acting on a 1 kg mass produces an acceleration of 1 m/s2 in it, the force is called one newton.
Linear momentum :
The product of the mass of a body and its velocity is called the linear momentum of the body.
The net force on a body is equal to change in its momentum per unit time.
Conservation of linear momentum :
If the net external force acting on a system of particles is zero, the total linear momentum of the system remains constant.0
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10min
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Gravitation Part 1 (Physics) - Lecture 9
1. The force of attraction between two bodies in the universe is known as gravitational force.
2. Gravitational force between two bodies of masses m1 and m2 separated by a distance r is given by
F =
3. G = 6.673 × 10–11 Nm2 kg–2 is gravitational constant.
4. Gravitational force is large if masses of two bodies are very large.
5. Gravitational force of the earth on a body is known as gravity.
6. The fall of a body is known as free fall if it falls only under the action of gravitational force of earth in the absence of air resistance.
7. Acceleration with which a body falls towards the earth, the gravitational force of the earth is called acceleration due to gravity. It is denoted by 'g'.
8. In S.I., unit of 'g' is m s–2.
9. g=, where M is the mass of the earth and R is the radius of the earth.
10. The value of 'g' on the surface of the earth is 9.8 m s–2.
11. The value of 'g' on the surface of the moon = 1/6 times value of 'g' on the surface of the earth.
12. The value of 'g' decreases with height and depth from surface of the earth.
13. The value of 'g' at poles is more than at equator.
14. The value of 'g' is zero at the centre of the earth.
15. Mass is the quantity of matter contained in a body.
16. In S.I. unit of mass is kg.
17. Weight of a body is the force with which the earth attracts the body. Weight of body always acts at its centre of gravity and in the downward direction, W = mg.
18. In S.I., unit of weight is newton (N).
19. Mass of a body does not change but weight of a body is different at different places.
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16min
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Gravitation Part 2 (Physics) - Lecture 10
1. The force of attraction between two bodies in the universe is known as gravitational force.
2. Gravitational force between two bodies of masses m1 and m2 separated by a distance r is given by
F =
3. G = 6.673 × 10–11 Nm2 kg–2 is gravitational constant.
4. Gravitational force is large if masses of two bodies are very large.
5. Gravitational force of the earth on a body is known as gravity.
6. The fall of a body is known as free fall if it falls only under the action of gravitational force of earth in the absence of air resistance.
7. Acceleration with which a body falls towards the earth, the gravitational force of the earth is called acceleration due to gravity. It is denoted by 'g'.
8. In S.I., unit of 'g' is m s–2.
9. g=, where M is the mass of the earth and R is the radius of the earth.
10. The value of 'g' on the surface of the earth is 9.8 m s–2.
11. The value of 'g' on the surface of the moon = 1/6 times value of 'g' on the surface of the earth.
12. The value of 'g' decreases with height and depth from surface of the earth.
13. The value of 'g' at poles is more than at equator.
14. The value of 'g' is zero at the centre of the earth.
15. Mass is the quantity of matter contained in a body.
16. In S.I. unit of mass is kg.
17. Weight of a body is the force with which the earth attracts the body. Weight of body always acts at its centre of gravity and in the downward direction, W = mg.
18. In S.I., unit of weight is newton (N).
19. Mass of a body does not change but weight of a body is different at different places.
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37min
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Gravitation Numerical Part 3 (Physics) - Lecture 11
1. The force of attraction between two bodies in the universe is known as gravitational force.
2. Gravitational force between two bodies of masses m1 and m2 separated by a distance r is given by
F =
3. G = 6.673 × 10–11 Nm2 kg–2 is gravitational constant.
4. Gravitational force is large if masses of two bodies are very large.
5. Gravitational force of the earth on a body is known as gravity.
6. The fall of a body is known as free fall if it falls only under the action of gravitational force of earth in the absence of air resistance.
7. Acceleration with which a body falls towards the earth, the gravitational force of the earth is called acceleration due to gravity. It is denoted by 'g'.
8. In S.I., unit of 'g' is m s–2.
9. g=, where M is the mass of the earth and R is the radius of the earth.
10. The value of 'g' on the surface of the earth is 9.8 m s–2.
11. The value of 'g' on the surface of the moon = 1/6 times value of 'g' on the surface of the earth.
12. The value of 'g' decreases with height and depth from surface of the earth.
13. The value of 'g' at poles is more than at equator.
14. The value of 'g' is zero at the centre of the earth.
15. Mass is the quantity of matter contained in a body.
16. In S.I. unit of mass is kg.
17. Weight of a body is the force with which the earth attracts the body. Weight of body always acts at its centre of gravity and in the downward direction, W = mg.
18. In S.I., unit of weight is newton (N).
19. Mass of a body does not change but weight of a body is different at different places.
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16min
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Sound Part 1 (Physics) - Lecture 12
1. Sound : Sound is a form of energy which produces a sensation of hearing in our ears.
2. Source of sound and its propagation : A source of vibration motion of an object is normally a source of sound.
3. Characteristics of the medium required for the propagation of sound:
(i) Medium must be elastic so that the medium particles have the tendency to return back to their original positions after the displacement.
(ii) Medium must have the inertia so that its particles have the capacity to store the energy.
The frictional resistance of the medium should be negligible to minimise the loss of energy in propagation.
4. Types of waves
(i) Mechanical waves : A mechanical wave is a periodic disturbance which requires a material medium for its propagation. On the basis of motion of particles the mechanical waves are classified into two parts.
(a) Transverse wave
(b) Longitudinal wave
(a) Transverse wave : When the particles of the medium vibrate in a direction perpendicular to the direction of propagation of the wave, the wave is known as the transverse wave. For example, waves produced in a stretched string.
(b) Longitudinal wave : When the particles of the medium vibrate along the direction of propagation of the wave then the wave is known as the longitudinal wave. For example sound wave in air.
(ii) Electromagnetic waves : The waves which do not require medium for propagation are called electromagnetic waves these waves can travel through vacuum also. For example, light waves, X-rays.
5. Characteristics of a sound wave
Frequency : The number of vibrations per second is called frequency.
The unit of frequency is hertz
(ii) Amplitude: The maximum displacement of each particle from its mean position is called amplitude.
The S.I. unit of amplitude is metre (m).
(iii) Time period: The time taken to complete one vibration is called time period.
Frequency= 1/(Time period) or v = 1/T
(iv) Wavelength: The distance between two nearest (adjacent) crests or troughs of a wave is called its wavelength.
(v) Velocity of wave: The distance travelled by a wave in one second is called velocity of the wave (or speed of the wave). The S.I. unit for the velocity of a wave is metres per second (m/s or ms-1).
(vi) Pitch : Pitch is the sensation (brain interpretation) of the frequency of an emitted sound and is the characteristic which distinguishes a shrill (or sharp) sound from a grave (or flat) sound.
(vii) Loudness : It is a measure of the sound energy reaching the ear per second.
6. Reflection of sound : When sound waves strike a surface, they return back into the same medium. This phenomenon is called reflection.
7. Laws of reflection : Angle of incidence is equal the angle of reflection.
The incident wave, the reflected wave and the normal all lie in the same plane.
8. Echo : Phenomenon of hearing back our own sound is called an echo. It is due to successive reflection from the surfaces obstacles of large size.
9. Relation between speed of sound, time of hearing echo and distance of reflection body :Ift is the time at which an echo is heard, d is the distance between the source of sound and the reflecting body and v is the speed of sound. The total distance travelled by the sound is 2d.
speed of sound, v = 2d/t or d = vt/2
10. Conditions for the formation of Echoes
(i) The minimum distance between the source of sound and the reflecting body should be 17.2 metres.
(ii) The wavelength of sound should be less than the height of the reflecting body.
(iii) The intensity of sound should be sufficient so that it can be heard after reflection.
11. Reverberation : Persistence of sound after its production is stopped, is called reverberation. A short reverberation is desirable in a concert hall (where music is being played) because it gives ‘life’ to sound. Too much reverberation confuses the programmers and must be reduced to reduce reverberation.
12. Range of Hearing : The audible range of sound for human beings extends from about 20 Hz to 20,000 Hz (one Hz = one cycle/s). Sounds of frequencies below 20 Hz are called infrasonic sound or infrasound. Frequencies higher than 20 kHz are called ultrasonic sound or ultra sound. Ultrasound is produced by dolphins.
13. Applications of ultrasound : The ultrasound is commonly used for medical diagnosis and therapy, and also as a surgical tool. It is also used in a wide variety of industrial applications and processes. Some creatures use ultrasound for information exchange and for the detection and location of objects. Also some bats and
porpoises are found to use ultrasound for navi gation and to locate food in darkness or at a place where there is inadequate light for vision (method of search is called echolocation).
14. Sonar : SONAR means Sound Navigation Rang-ing. In this sound waves (ultrasonic) are used [microwaves are absorbed by water)]. Sound waves are emitted by a source. These waves travel in water with velocity v. The waves re-flected by targets (like submarine bottom sea) are detected.
Uses
(i) The SONAR system is used for detecting the presence of unseen underwater objects, such as a submerged submarine, a sunken ship, sea rock or a hidden iceberg, and locating them accurately.
(ii) The principle of SONAR is also used in industry of detection of flaws in metal blocks or sheets without damaging them.
15. Human ear : It is a highly sensitive part of the human body which enables us to hear a sound. It converts the pressure variations in air with audiable frequencies into electric signals which travel to the brain via the auditory nerve.
The human ear has three main parts. Their auditory functions are as follows:
(i) Outer ear : The outer ear is called `pinna’. It collects the sound from the suri-ounding. The collected sound passes through the auditory canal. At the end of the auditory canal there is a thin membrane called the ear drum or tympanic membrane. When compression of the medium produced due to vibration of the object reaches the ear drum, the pressure on the outside of the membrane increases and forces the eardrum inward. Similarly, the eardrum moves outward when a rarefaction reaches. In this way the ear drum vibrates.
(ii) Middle ear: The vibrations are amplified several times by three bones (the hammer, anvil and stirrup) in the middle ear which act as levers. The middle ear transmits the amplified pressure variations received from the sound wave to the inner ear.
(iii) Inner ear: In the inner ear, the pressure variations are turned into electrical signals by the cochlea. These electrical signals are sent to the brain via the auditory nerve, and the brain interprets them as sound.
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20min
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Sound Part 2 (Physics) - Lecture 13
1. Sound : Sound is a form of energy which produces a sensation of hearing in our ears.
2. Source of sound and its propagation : A source of vibration motion of an object is normally a source of sound.
3. Characteristics of the medium required for the propagation of sound:
(i) Medium must be elastic so that the medium particles have the tendency to return back to their original positions after the displacement.
(ii) Medium must have the inertia so that its particles have the capacity to store the energy.
The frictional resistance of the medium should be negligible to minimise the loss of energy in propagation.
4. Types of waves
(i) Mechanical waves : A mechanical wave is a periodic disturbance which requires a material medium for its propagation. On the basis of motion of particles the mechanical waves are classified into two parts.
(a) Transverse wave
(b) Longitudinal wave
(a) Transverse wave : When the particles of the medium vibrate in a direction perpendicular to the direction of propagation of the wave, the wave is known as the transverse wave. For example, waves produced in a stretched string.
(b) Longitudinal wave : When the particles of the medium vibrate along the direction of propagation of the wave then the wave is known as the longitudinal wave. For example sound wave in air.
(ii) Electromagnetic waves : The waves which do not require medium for propagation are called electromagnetic waves these waves can travel through vacuum also. For example, light waves, X-rays.
5. Characteristics of a sound wave
Frequency : The number of vibrations per second is called frequency.
The unit of frequency is hertz
(ii) Amplitude: The maximum displacement of each particle from its mean position is called amplitude.
The S.I. unit of amplitude is metre (m).
(iii) Time period: The time taken to complete one vibration is called time period.
Frequency= 1/(Time period) or v = 1/T
(iv) Wavelength: The distance between two nearest (adjacent) crests or troughs of a wave is called its wavelength.
(v) Velocity of wave: The distance travelled by a wave in one second is called velocity of the wave (or speed of the wave). The S.I. unit for the velocity of a wave is metres per second (m/s or ms-1).
(vi) Pitch : Pitch is the sensation (brain interpretation) of the frequency of an emitted sound and is the characteristic which distinguishes a shrill (or sharp) sound from a grave (or flat) sound.
(vii) Loudness : It is a measure of the sound energy reaching the ear per second.
6. Reflection of sound : When sound waves strike a surface, they return back into the same medium. This phenomenon is called reflection.
7. Laws of reflection : Angle of incidence is equal the angle of reflection.
The incident wave, the reflected wave and the normal all lie in the same plane.
8. Echo : Phenomenon of hearing back our own sound is called an echo. It is due to successive reflection from the surfaces obstacles of large size.
9. Relation between speed of sound, time of hearing echo and distance of reflection body :Ift is the time at which an echo is heard, d is the distance between the source of sound and the reflecting body and v is the speed of sound. The total distance travelled by the sound is 2d.
speed of sound, v = 2d/t or d = vt/2
10. Conditions for the formation of Echoes
(i) The minimum distance between the source of sound and the reflecting body should be 17.2 metres.
(ii) The wavelength of sound should be less than the height of the reflecting body.
(iii) The intensity of sound should be sufficient so that it can be heard after reflection.
11. Reverberation : Persistence of sound after its production is stopped, is called reverberation. A short reverberation is desirable in a concert hall (where music is being played) because it gives ‘life’ to sound. Too much reverberation confuses the programmers and must be reduced to reduce reverberation.
12. Range of Hearing : The audible range of sound for human beings extends from about 20 Hz to 20,000 Hz (one Hz = one cycle/s). Sounds of frequencies below 20 Hz are called infrasonic sound or infrasound. Frequencies higher than 20 kHz are called ultrasonic sound or ultra sound. Ultrasound is produced by dolphins.
13. Applications of ultrasound : The ultrasound is commonly used for medical diagnosis and therapy, and also as a surgical tool. It is also used in a wide variety of industrial applications and processes. Some creatures use ultrasound for information exchange and for the detection and location of objects. Also some bats and
porpoises are found to use ultrasound for navi gation and to locate food in darkness or at a place where there is inadequate light for vision (method of search is called echolocation).
14. Sonar : SONAR means Sound Navigation Rang-ing. In this sound waves (ultrasonic) are used [microwaves are absorbed by water)]. Sound waves are emitted by a source. These waves travel in water with velocity v. The waves re-flected by targets (like submarine bottom sea) are detected.
Uses
(i) The SONAR system is used for detecting the presence of unseen underwater objects, such as a submerged submarine, a sunken ship, sea rock or a hidden iceberg, and locating them accurately.
(ii) The principle of SONAR is also used in industry of detection of flaws in metal blocks or sheets without damaging them.
15. Human ear : It is a highly sensitive part of the human body which enables us to hear a sound. It converts the pressure variations in air with audiable frequencies into electric signals which travel to the brain via the auditory nerve.
The human ear has three main parts. Their auditory functions are as follows:
(i) Outer ear : The outer ear is called `pinna’. It collects the sound from the suri-ounding. The collected sound passes through the auditory canal. At the end of the auditory canal there is a thin membrane called the ear drum or tympanic membrane. When compression of the medium produced due to vibration of the object reaches the ear drum, the pressure on the outside of the membrane increases and forces the eardrum inward. Similarly, the eardrum moves outward when a rarefaction reaches. In this way the ear drum vibrates.
(ii) Middle ear: The vibrations are amplified several times by three bones (the hammer, anvil and stirrup) in the middle ear which act as levers. The middle ear transmits the amplified pressure variations received from the sound wave to the inner ear.
(iii) Inner ear: In the inner ear, the pressure variations are turned into electrical signals by the cochlea. These electrical signals are sent to the brain via the auditory nerve, and the brain interprets them as sound.
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11min
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Electric Current Part 1 (Physics) - Lecture 15
Electric current : An electric current is defined as the amount of charge flowing through any
cross-section of a conductor per unit time, I = . Electric current is a scalar quantity.
Electric current in terms of number of electrons (n) in a conductor, I = ,
e = charge on an electron = –1.6 × 10–19 C.
In a metallic wire or conductor, the flow of electric current is due to the flow of electrons from one end to the other end of the wire.
Charge carrier in a metallic wire are conduction elements.
6.25 × 1018 electrons make one coulomb of charge.
S.I. unit of electric current is ampere (A).
Ampere (A) : Electric current through a conductor is said to be 1 ampere if one coulomb charge flows through any cross-section of the conductor in one second.
Ammeter is used to measure electric current.
Ammeter is always connected in series in an electric circuit.
Electric potential is defined as work done per unit charge.
V =
Electric potential is a scalar quantity.
Electric potential difference is defined as the work done in moving a unit positive charge from one point to another point.
dV =
SI unit of electric potential is volt (V).
Voltmeter is used to measure the potential difference between two points in an electric circuit.
Voltmeter is always connected in parallel in an electric circuit.
Ohm's Law : This law states that, "the electric current flowing in a conductor is directly proportional to the potential difference across the ends of the conductor, provided the temperature and other physical conditions of the conductor remain the same".
Resistance (R) : Resistance of a conductor is the ability of the conductor to oppose the flow of charge through it.
Unit of resistance is ohm.
1 Ohm : Resistance of a conductor is said to be 1 ohm if a potential difference of 1 volt across the ends of the conductor produces a current of 1 ampere through it.
Resistor is a component (say a metallic wire) in an electric circuit which offers resistance to the flow of electrons constituting the electric current in the electric circuit.
Law of Resistance :
(i) Resistance of a conductor depends upon the nature of the material of the conductor.
(ii) Resistance of a conductor is directly proportional to the length of the conductor.
(iii) Resistance of a conductor is inversely proportional to the each of cross-section of the conductor.
(iv) Resistance of metallic conductor increases with the increase of temperature and decreases with the decrease of the temperature.
R =
Resistivity or Specific Resistance () : Resistivity is defined as the resistance of the conductor of unit length and unit area of cross-section.
Unit of Resistivity :
In CGS system, unit if resistivity is ohm-cm.
In SI system, unit of resistivity is ohm-metre.
Two or more resistors are said to be connected in series if same amount of current flows through these resistors.
The effective resistance of series combination of resistors is the algebraic sum of the individual resistances of the resistors in the combination.
An electric bulb or a heater or a metallic wire acts as a resistor.
If one of the electric bulbs connected in a series is fused, then no electric bulb will glow inspite of the fact that the combination is connected with a source of electric current.
Two or more resistors are said to be connected in parallel if the potential difference across each resistor is equal to the applied potential difference across the combination of the resistors.
The effective resistance of the resistors connected in parallel is less than the minimum resistance of a resistor in the combination.
Resistors are connected in series if the resistance of the electric circuit is to be increased.
Resistors are connected in parallel if the resistance of the electric circuit is to be decreased.
Joule's Law of Heating :
The amount of heat produced in a conductor is
(i) Directly proportional to the square of the electric current flowing through it.
(ii) Directly proportional to the resistance of the conductor.
(iii) Directly proportional to the time for which the electric current flows through the conductor.
H = I2Rt (joule)
Electric fuse is a safety device used to save the electric appliances from burning.
Electric fuse is a wire made of a material having low melting point.
Electric fuse wire is made of copper or tin-lead alloy.
Electric energy : The work done by a source of electricity to maintain a current in an electric circuit is known as electric energy.
E = VIt
Electric power : Electric power is defined as the amount of electric work done in one second.
P = VI = I2R = V2 / R
SI unit of power is watt.
Practical unit of power is horse power (h.p.)
1 h.p. = 746 W
Electric energy = Electric power × time
Commercial unit of Energy : kilowatt-hour (kWh)
1 kWh = 3.6 × 106 J
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29min
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Electric Current Part 2 (Physics) - Lecture 16
Electric current : An electric current is defined as the amount of charge flowing through any
cross-section of a conductor per unit time, I = . Electric current is a scalar quantity.
Electric current in terms of number of electrons (n) in a conductor, I = ,
e = charge on an electron = –1.6 × 10–19 C.
In a metallic wire or conductor, the flow of electric current is due to the flow of electrons from one end to the other end of the wire.
Charge carrier in a metallic wire are conduction elements.
6.25 × 1018 electrons make one coulomb of charge.
S.I. unit of electric current is ampere (A).
Ampere (A) : Electric current through a conductor is said to be 1 ampere if one coulomb charge flows through any cross-section of the conductor in one second.
Ammeter is used to measure electric current.
Ammeter is always connected in series in an electric circuit.
Electric potential is defined as work done per unit charge.
V =
Electric potential is a scalar quantity.
Electric potential difference is defined as the work done in moving a unit positive charge from one point to another point.
dV =
SI unit of electric potential is volt (V).
Voltmeter is used to measure the potential difference between two points in an electric circuit.
Voltmeter is always connected in parallel in an electric circuit.
Ohm's Law : This law states that, "the electric current flowing in a conductor is directly proportional to the potential difference across the ends of the conductor, provided the temperature and other physical conditions of the conductor remain the same".
Resistance (R) : Resistance of a conductor is the ability of the conductor to oppose the flow of charge through it.
Unit of resistance is ohm.
1 Ohm : Resistance of a conductor is said to be 1 ohm if a potential difference of 1 volt across the ends of the conductor produces a current of 1 ampere through it.
Resistor is a component (say a metallic wire) in an electric circuit which offers resistance to the flow of electrons constituting the electric current in the electric circuit.
Law of Resistance :
(i) Resistance of a conductor depends upon the nature of the material of the conductor.
(ii) Resistance of a conductor is directly proportional to the length of the conductor.
(iii) Resistance of a conductor is inversely proportional to the each of cross-section of the conductor.
(iv) Resistance of metallic conductor increases with the increase of temperature and decreases with the decrease of the temperature.
R =
Resistivity or Specific Resistance () : Resistivity is defined as the resistance of the conductor of unit length and unit area of cross-section.
Unit of Resistivity :
In CGS system, unit if resistivity is ohm-cm.
In SI system, unit of resistivity is ohm-metre.
Two or more resistors are said to be connected in series if same amount of current flows through these resistors.
The effective resistance of series combination of resistors is the algebraic sum of the individual resistances of the resistors in the combination.
An electric bulb or a heater or a metallic wire acts as a resistor.
If one of the electric bulbs connected in a series is fused, then no electric bulb will glow inspite of the fact that the combination is connected with a source of electric current.
Two or more resistors are said to be connected in parallel if the potential difference across each resistor is equal to the applied potential difference across the combination of the resistors.
The effective resistance of the resistors connected in parallel is less than the minimum resistance of a resistor in the combination.
Resistors are connected in series if the resistance of the electric circuit is to be increased.
Resistors are connected in parallel if the resistance of the electric circuit is to be decreased.
Joule's Law of Heating :
The amount of heat produced in a conductor is
(i) Directly proportional to the square of the electric current flowing through it.
(ii) Directly proportional to the resistance of the conductor.
(iii) Directly proportional to the time for which the electric current flows through the conductor.
H = I2Rt (joule)
Electric fuse is a safety device used to save the electric appliances from burning.
Electric fuse is a wire made of a material having low melting point.
Electric fuse wire is made of copper or tin-lead alloy.
Electric energy : The work done by a source of electricity to maintain a current in an electric circuit is known as electric energy.
E = VIt
Electric power : Electric power is defined as the amount of electric work done in one second.
P = VI = I2R = V2 / R
SI unit of power is watt.
Practical unit of power is horse power (h.p.)
1 h.p. = 746 W
Electric energy = Electric power × time
Commercial unit of Energy : kilowatt-hour (kWh)
1 kWh = 3.6 × 106 J
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17min
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Electric Current Part 3 (Physics) - Lecture 17
Electric current : An electric current is defined as the amount of charge flowing through any
cross-section of a conductor per unit time, I = . Electric current is a scalar quantity.
Electric current in terms of number of electrons (n) in a conductor, I = ,
e = charge on an electron = –1.6 × 10–19 C.
In a metallic wire or conductor, the flow of electric current is due to the flow of electrons from one end to the other end of the wire.
Charge carrier in a metallic wire are conduction elements.
6.25 × 1018 electrons make one coulomb of charge.
S.I. unit of electric current is ampere (A).
Ampere (A) : Electric current through a conductor is said to be 1 ampere if one coulomb charge flows through any cross-section of the conductor in one second.
Ammeter is used to measure electric current.
Ammeter is always connected in series in an electric circuit.
Electric potential is defined as work done per unit charge.
V =
Electric potential is a scalar quantity.
Electric potential difference is defined as the work done in moving a unit positive charge from one point to another point.
dV =
SI unit of electric potential is volt (V).
Voltmeter is used to measure the potential difference between two points in an electric circuit.
Voltmeter is always connected in parallel in an electric circuit.
Ohm's Law : This law states that, "the electric current flowing in a conductor is directly proportional to the potential difference across the ends of the conductor, provided the temperature and other physical conditions of the conductor remain the same".
Resistance (R) : Resistance of a conductor is the ability of the conductor to oppose the flow of charge through it.
Unit of resistance is ohm.
1 Ohm : Resistance of a conductor is said to be 1 ohm if a potential difference of 1 volt across the ends of the conductor produces a current of 1 ampere through it.
Resistor is a component (say a metallic wire) in an electric circuit which offers resistance to the flow of electrons constituting the electric current in the electric circuit.
Law of Resistance :
(i) Resistance of a conductor depends upon the nature of the material of the conductor.
(ii) Resistance of a conductor is directly proportional to the length of the conductor.
(iii) Resistance of a conductor is inversely proportional to the each of cross-section of the conductor.
(iv) Resistance of metallic conductor increases with the increase of temperature and decreases with the decrease of the temperature.
R =
Resistivity or Specific Resistance () : Resistivity is defined as the resistance of the conductor of unit length and unit area of cross-section.
Unit of Resistivity :
In CGS system, unit if resistivity is ohm-cm.
In SI system, unit of resistivity is ohm-metre.
Two or more resistors are said to be connected in series if same amount of current flows through these resistors.
The effective resistance of series combination of resistors is the algebraic sum of the individual resistances of the resistors in the combination.
An electric bulb or a heater or a metallic wire acts as a resistor.
If one of the electric bulbs connected in a series is fused, then no electric bulb will glow inspite of the fact that the combination is connected with a source of electric current.
Two or more resistors are said to be connected in parallel if the potential difference across each resistor is equal to the applied potential difference across the combination of the resistors.
The effective resistance of the resistors connected in parallel is less than the minimum resistance of a resistor in the combination.
Resistors are connected in series if the resistance of the electric circuit is to be increased.
Resistors are connected in parallel if the resistance of the electric circuit is to be decreased.
Joule's Law of Heating :
The amount of heat produced in a conductor is
(i) Directly proportional to the square of the electric current flowing through it.
(ii) Directly proportional to the resistance of the conductor.
(iii) Directly proportional to the time for which the electric current flows through the conductor.
H = I2Rt (joule)
Electric fuse is a safety device used to save the electric appliances from burning.
Electric fuse is a wire made of a material having low melting point.
Electric fuse wire is made of copper or tin-lead alloy.
Electric energy : The work done by a source of electricity to maintain a current in an electric circuit is known as electric energy.
E = VIt
Electric power : Electric power is defined as the amount of electric work done in one second.
P = VI = I2R = V2 / R
SI unit of power is watt.
Practical unit of power is horse power (h.p.)
1 h.p. = 746 W
Electric energy = Electric power × time
Commercial unit of Energy : kilowatt-hour (kWh)
1 kWh = 3.6 × 106 J
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11min
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Magnetic Effect of Electric Current Part 1 (Physics) - Lecture 18
Hans Christian oersted discovered a relationship between electricity and magnetism.
A current carrying wire behaves as a magnet.
When a current passes through a wire, a magnetic field is set up around the wire. This effect of current is called magnetic effect of current.
Like magnetic poles repel each other and unlike magnetic poles attract each other.
Magnetic field is space or region around a current carrying wire or a magnet within which its influence is felt by another magnet.
Magnetic field line : The path along which a free unit north pole moves in a magnetic field is called magnetic field line. The tangent at any point on a magnetic field line gives the direction of the magnetic field at that point.
Two magnetic field lines can't intersect or cross each other.
Magnetic field lines are crowded in a region of strong magnetic field.
Magnetic field lines are far apart in a region of weak magnetic field.
When current passes through a straight wire or conductor, a magnetic field is set up around the wire or conductor.
Magnetic field around a current carrying wire or conductor is represented by concentric circles centred at the wire or the conductor.
The direction of magnetic field around the current carrying conductor is determined by Right Hand Thumb Rule.
Magnetic field around a current carrying wire increases with the increase in the current passing through the wire.
Magnetic field around a current carrying wire or conductor is represented by concentric circles centred at the wire or the conductor.
The direction of magnetic field around the current carrying conductor is determined by Right Hand Thumb Rule.
Magnetic field around a current carrying wire increases with the increase in the current passing through the wire.
Magnetic field around a current carrying wire decreases as we go away from the wire.
Magnetic field due to a very long wire like a power transmission line carrying current I and at a distance r from the wire is given by
B = ; where, µ0 = 4 × 10–7 TmA–1
Two parallel wires or conductors carrying current in the same directs attract each other.
Two parallel wires or conductors carrying current in the opposite directions repel each other.
The magnetic field around a straight current carrying conductor or wire can be increased by bending it into a circular loop.
The strength of magnetic field produced at the centre of a circular loop of a wire is
(i) directly proportional to the amount of current passing through the loop of the wire.
(ii) directly proportional to the number of turns of the circular loop of the wire.
(iii) inversely proportional to the radius of the circular loop of the wire.
Magnetic field produced by a current carrying circular wire or loop decreases on both sides along the axis of the circular wire.
A solenoid is a coil of many turns of an insulated copper wire closely wound in the shape of a tight spring.
Magnetic field inside a current carrying solenoid is uniform magnetic field.
A solenoid carrying current behaves like a bar magnet.
A soft iron rod placed in a current carrying solenoid is known as electromagnet.
A current carrying conductor placed perpendicular to the magnetic field experience a force.
The force acting on a current carrying conductor placed perpendicular to the magnetic field B is given by
F = BIl
Direction of force experienced by a current carrying conductor placed in a magnetic field is determined by Fleming’s Left Hand Rule.
No Force acts on a current carrying conductor when placed parallel to the magnetic field.
SI unit of magnetic field is tesla (T).
Force acts on a charge moving perpendicular to the magnetic field. This force is called Lorentz force.
Force acting on a charge Q moving with velocity v perpendicular to the magnetic field B is given by
F = BQV
No force acts on a charge moving parallel to the magnetic field B.
Direction of force experienced by a moving charge in a magnetic field is determined by Right Hand Rule.
Electric motor is a device which converts electrical energy into mechanical energy.
Principle of electric motor : Electric motor works on the principle that a current carrying conductor placed perpendicular to a magnetic field experiences a force.
The phenomenon of producing induced current in a closed circuit due to the change in magnetic field in the circuit is known as electromagnetic induction.
More induced current flows through a closed coil if a bar magnet is brought towards or away from the coil with large speed.
No induced current flows through a closed coil if magnetic field linked with it does not change.
Direction of induced current in a conductor is determined by Fleming’s Right hand rule.
Direct current is an electric current whose magnitude is either constant or variable but the direction of flow in a conductor remains the same.
Frequency of direct current is zero.
Alternating current is an electric current whose magnitude changes with time and direction reverse periodically.
In India, frequency of A.C. is 50 Hz.
A.C. is more dangerous than D.C.
Electric generator is a device used to convert mechanical energy into electrical energy.
Electric generator works on the principle of electromagnetic induction.
To supply electric power from one place to another place, three wires known as phase wire (or live wire), neutral wire and earth wire are used.
The potential difference between the live wire and neutral wire in a household supply of electric power is 220 V.
Current rating of a fuse is the maximum amount of electric current that can be passed through the fuse wire without melting it.
Current rating of a fuse wire in a circuit having bulbs and tubes is 5A.
Current rating of a fuse wire in a circuit having heating appliances is 15A.
Electric fuse is a safety device used to save the electrical appliances from burning when large current flows in the circuit.
Electric fuse is made of a material of low melting point.
Material used for making a fuse wire is made of copper / aluminium / tin-lead alloy.
Short Circuiting : When live wire and neutral wire come in direct contact, the resistance of the circuit becomes very small. Hence huge current flows through the circuit. This huge current produces large amount of heat in the circuit and the circuit catches fire. This is known as short circuiting.
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21min
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Magnetic Effect of Electric Current Part 2 (Physics) - Lecture 19
Hans Christian oersted discovered a relationship between electricity and magnetism.
A current carrying wire behaves as a magnet.
When a current passes through a wire, a magnetic field is set up around the wire. This effect of current is called magnetic effect of current.
Like magnetic poles repel each other and unlike magnetic poles attract each other.
Magnetic field is space or region around a current carrying wire or a magnet within which its influence is felt by another magnet.
Magnetic field line : The path along which a free unit north pole moves in a magnetic field is called magnetic field line. The tangent at any point on a magnetic field line gives the direction of the magnetic field at that point.
Two magnetic field lines can't intersect or cross each other.
Magnetic field lines are crowded in a region of strong magnetic field.
Magnetic field lines are far apart in a region of weak magnetic field.
When current passes through a straight wire or conductor, a magnetic field is set up around the wire or conductor.
Magnetic field around a current carrying wire or conductor is represented by concentric circles centred at the wire or the conductor.
The direction of magnetic field around the current carrying conductor is determined by Right Hand Thumb Rule.
Magnetic field around a current carrying wire increases with the increase in the current passing through the wire.
Magnetic field around a current carrying wire or conductor is represented by concentric circles centred at the wire or the conductor.
The direction of magnetic field around the current carrying conductor is determined by Right Hand Thumb Rule.
Magnetic field around a current carrying wire increases with the increase in the current passing through the wire.
Magnetic field around a current carrying wire decreases as we go away from the wire.
Magnetic field due to a very long wire like a power transmission line carrying current I and at a distance r from the wire is given by
B = ; where, µ0 = 4 × 10–7 TmA–1
Two parallel wires or conductors carrying current in the same directs attract each other.
Two parallel wires or conductors carrying current in the opposite directions repel each other.
The magnetic field around a straight current carrying conductor or wire can be increased by bending it into a circular loop.
The strength of magnetic field produced at the centre of a circular loop of a wire is
(i) directly proportional to the amount of current passing through the loop of the wire.
(ii) directly proportional to the number of turns of the circular loop of the wire.
(iii) inversely proportional to the radius of the circular loop of the wire.
Magnetic field produced by a current carrying circular wire or loop decreases on both sides along the axis of the circular wire.
A solenoid is a coil of many turns of an insulated copper wire closely wound in the shape of a tight spring.
Magnetic field inside a current carrying solenoid is uniform magnetic field.
A solenoid carrying current behaves like a bar magnet.
A soft iron rod placed in a current carrying solenoid is known as electromagnet.
A current carrying conductor placed perpendicular to the magnetic field experience a force.
The force acting on a current carrying conductor placed perpendicular to the magnetic field B is given by
F = BIl
Direction of force experienced by a current carrying conductor placed in a magnetic field is determined by Fleming’s Left Hand Rule.
No Force acts on a current carrying conductor when placed parallel to the magnetic field.
SI unit of magnetic field is tesla (T).
Force acts on a charge moving perpendicular to the magnetic field. This force is called Lorentz force.
Force acting on a charge Q moving with velocity v perpendicular to the magnetic field B is given by
F = BQV
No force acts on a charge moving parallel to the magnetic field B.
Direction of force experienced by a moving charge in a magnetic field is determined by Right Hand Rule.
Electric motor is a device which converts electrical energy into mechanical energy.
Principle of electric motor : Electric motor works on the principle that a current carrying conductor placed perpendicular to a magnetic field experiences a force.
The phenomenon of producing induced current in a closed circuit due to the change in magnetic field in the circuit is known as electromagnetic induction.
More induced current flows through a closed coil if a bar magnet is brought towards or away from the coil with large speed.
No induced current flows through a closed coil if magnetic field linked with it does not change.
Direction of induced current in a conductor is determined by Fleming’s Right hand rule.
Direct current is an electric current whose magnitude is either constant or variable but the direction of flow in a conductor remains the same.
Frequency of direct current is zero.
Alternating current is an electric current whose magnitude changes with time and direction reverse periodically.
In India, frequency of A.C. is 50 Hz.
A.C. is more dangerous than D.C.
Electric generator is a device used to convert mechanical energy into electrical energy.
Electric generator works on the principle of electromagnetic induction.
To supply electric power from one place to another place, three wires known as phase wire (or live wire), neutral wire and earth wire are used.
The potential difference between the live wire and neutral wire in a household supply of electric power is 220 V.
Current rating of a fuse is the maximum amount of electric current that can be passed through the fuse wire without melting it.
Current rating of a fuse wire in a circuit having bulbs and tubes is 5A.
Current rating of a fuse wire in a circuit having heating appliances is 15A.
Electric fuse is a safety device used to save the electrical appliances from burning when large current flows in the circuit.
Electric fuse is made of a material of low melting point.
Material used for making a fuse wire is made of copper / aluminium / tin-lead alloy.
Short Circuiting : When live wire and neutral wire come in direct contact, the resistance of the circuit becomes very small. Hence huge current flows through the circuit. This huge current produces large amount of heat in the circuit and the circuit catches fire. This is known as short circuiting.
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7min
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Source of Energy (Physics) - Lecture 20
Energy is the essential requirement for each and every activity in our life.
The various sources of energy are the sun, the wind, water, fossil fuels etc.
The sun is the ultimate source of all forms of energy.
A good source of energy is one which supplies large amount of useful energy, easily available, economical and cause minimum environmental pollution. .
Thermal power plant generates electricity by burning fossil fuel like coal and oil.
LPG is a petroleum gas liquefied under pressure. Its full form is liquefied Petroleum Gas.
CNG is compressed Natural Gas.
Main constituents of CNG is methane.
Electricity produced by flowing water is known as hydro - electric power.
A plant used to produce hydro -electric power is known as hydro -electric power plant.
Potential energy of water stored in a dam is converted into kinetic energy of the falling water. This kinetic energy of falling water is converted into the kinetic energy of the armature of the generator which in turn is converted into electric energy.
Biomass is material which contains carbon and other combustible material.
Plants, wood animals and plants waster are the examples of biomass.
Gobar gas or bio-gas is the example of a bio - mass energy source.
Main constituent of a biogas or gobar gas is a methane gas.
Biogas plant is of two types: (a) Fixed-dome type, (b) Floating gas holder type.
Kinetic energy of wind is known as wind energy.
Wind energy is used to produce electricity.
The region where large number of wind mills are erected to produce electricity is called wind energy farm.
The minimum speed of wind to operate generator to produce electricity is about 15 km/h.
Constant and rapid use of conventional sources of energy would ultimately exhaust these sources and hence a need for tapping energy from alternate or non-conventional sources of energy is seriously felt.
Solar energy is the energy emitted by the sun in the form of heat and light.
Solar constant is defined as the energy received from the sun in one second by a unit square metre area of the outer edge of earth's atmosphere exposed perpendicular to the radiation of the sun at an average distance between the sun and the earth.
Value of solar constant = 1.4 k W/m2.
Solar devices like solar cooker, solar furnace, solar water heater, solar panels and solar cells are used to harness solar energy.
Water due to its high specific heat capacity (4200 J kg–1°C–1) is a store house of heat energy.
Energy from sea or ocean water is available in the form of (i) energy of sea waves (ii) Tidal energy and (iii) Ocean thermal energy (OTE).
The heat energy obtained from the conversion of nuclear mass is known as nuclear energy.
Nuclear energy is obtained by two processes known as nuclear fission and nuclear fusion.
Nuclear energy is expressed in electron - volt(eV)
1 eV = 1.6 10–19J
1 MeV = 106 eV = 1.6 –13J
Nuclear Fission is the process of splitting a heavy nucleus (say Uranium) into two comparatively lower nuclei along with the release of large amount energy when bombarded with thermal neutron.
Nuclear reactor is a device used to carry out controlled chain reaction.
Nuclear fusion is the process of fusing or combining together two small nuclei to form a comparatively big nucleus with the release of large energy.
Nuclear fusion reactions occur at very high temperature (107K).
Nuclear fusion reactions occurring in the interior of the sun are responsible for the energy of the sun.
In other words, nuclear fusion reactions are the sources of energy of the sun.
Sources of energy are classified into two categories (i) conventional or non-renewable sources of energy and (ii) Non-conventional or renewable sources of energy.
Extraction and transportation of energy from various sources of energy cause environmental pollution.
The energy from various sources of energy must be used effectively to conserve energy.
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8min
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Light Part 1 (Physics) - Lecture 21
Light is a form of energy which produces the sensation of sight.
Speed of light in vacuum / air = 3 × 108 ms–1
Ray of light : A line drawn in the direction of propagation of light is called ray of light.
Beam of light : A group of parallel rays light emitted by a source of light is called beam of light.
Reflection of light : The phenomenon of returning of light in the same medium after striking a surface is called reflection of light.
Laws of reflection : The reflection of light from a surface obeys certain laws called laws of reflection.
(i) incident angle is equal to reflected angle i.e. i = r.
(ii) Incident ray, reflected ray and normal to the reflecting surface at the point on incident lie in the same plane.
Concave mirror : concave mirror is a part of a hollow sphere whose outer part is silvered and the inner part is reflecting surface.
Convex mirror : convex mirror is a part of a hollow sphere whose outer part is reflecting surface and inner part is silvered.
Centre of curvature : The centre of a hollow sphere of which the spherical mirror forms a part is called centre of curvature. It is denoted by C
Radius of curvature : The radius of a hollow sphere of which the spherical mirror forms a part is called radius of curvature. It is denoted by R
Pole : The mid point of a spherical mirror is called its pole. It is denoted by P
Aperture: The part of spherical mirror exposed to the incident light is called the aperture of the mirror.
Principal Axis: A line joining the centre of curvature (C) and pole (P) of a spherical mirror and extend on either side is called principal axis of the spherical mirror.
Principal Focus : A point on the principal axis of a spherical mirror where the rays of light parallel to the principal axis meet or appears to meet after reflection from the spherical mirror is called principal focus. It is denoted by F.
Focal Plane : A plane normal or perpendicular to the principal axis and passing through the principal focus (F) of the spherical mirror is called focal plane of the spherical mirror.
Focal length (f): The distance between the pole (P) and the principal focus (F) of a spherical mirror is called the focal length of the spherical mirror.
f = , Where R is the radius of the curvature of the mirror.
Focal length and radius of curvature of a concave mirror are negative.
Focal length and radius of curvature of a convex mirror are positive.
Sign Conventions for reflection by spherical mirrors
(1) All distance are measured from the pole of a spherical mirror.
(2) Distance measured in the direction of incident light are taken as positive. Distance measured in the direction opposite to that of the incident light are taken negative.
(3) The upward distance perpendicular to the principal axis are taken as positive, while the downward distance perpendicular to the principal axis are taken as negative.
Radius of curvature plane mirror = ( infinite)
Focal length of a plane mirror =
Mirror Formula : The relation between u, v, and focal length (f) of a spherical mirror is known as mirror formula.
That is
Linear magnification : Linear magnification produced by a mirror is defined as the ratio of the size
( or height) of the image to the size of the object . It is denoted by m.
That is
Power of mirror (P) = =
Linear magnification produced by a plane mirror = + 1.
Refraction of light: The bending of light rays when they pass obsessively from one medium to the other medium is called refraction of light .
A transparent medium through which light travels fast is known as optically rarer medium.
A transparent medium through which light travels slow is known as optically denser medium.
Laws of refraction
(i) The incident ray, the refracted ray and the normal to the surface separating two media all lie in the same plane.
(ii) The ratio of the sine of the incident angle (i) to the sine of the refracted angle (r) is constant
i.e. sin i/ sin r = constant
This constant is known as the refractive index of second medium w.r.t the first medium.
Absolute refractive index of a medium is defined as the ratio of the speed of light in vacuum (c) to the speed of light in the medium (v)
i.e. n = c / v
Relative refractive index of medium. 2 w.r.t. the medium 1 is defined as the ratio of the speed of light in medium 1 (v1) to the speed of light in medium 2 (v2).
i.e. n21= v2 / v1
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17min
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Light Numerical Part 2 (Physics) - Lecture 22
Light is a form of energy which produces the sensation of sight.
Speed of light in vacuum / air = 3 × 108 ms–1
Ray of light : A line drawn in the direction of propagation of light is called ray of light.
Beam of light : A group of parallel rays light emitted by a source of light is called beam of light.
Reflection of light : The phenomenon of returning of light in the same medium after striking a surface is called reflection of light.
Laws of reflection : The reflection of light from a surface obeys certain laws called laws of reflection.
(i) incident angle is equal to reflected angle i.e. i = r.
(ii) Incident ray, reflected ray and normal to the reflecting surface at the point on incident lie in the same plane.
Concave mirror : concave mirror is a part of a hollow sphere whose outer part is silvered and the inner part is reflecting surface.
Convex mirror : convex mirror is a part of a hollow sphere whose outer part is reflecting surface and inner part is silvered.
Centre of curvature : The centre of a hollow sphere of which the spherical mirror forms a part is called centre of curvature. It is denoted by C
Radius of curvature : The radius of a hollow sphere of which the spherical mirror forms a part is called radius of curvature. It is denoted by R
Pole : The mid point of a spherical mirror is called its pole. It is denoted by P
Aperture: The part of spherical mirror exposed to the incident light is called the aperture of the mirror.
Principal Axis: A line joining the centre of curvature (C) and pole (P) of a spherical mirror and extend on either side is called principal axis of the spherical mirror.
Principal Focus : A point on the principal axis of a spherical mirror where the rays of light parallel to the principal axis meet or appears to meet after reflection from the spherical mirror is called principal focus. It is denoted by F.
Focal Plane : A plane normal or perpendicular to the principal axis and passing through the principal focus (F) of the spherical mirror is called focal plane of the spherical mirror.
Focal length (f): The distance between the pole (P) and the principal focus (F) of a spherical mirror is called the focal length of the spherical mirror.
f = , Where R is the radius of the curvature of the mirror.
Focal length and radius of curvature of a concave mirror are negative.
Focal length and radius of curvature of a convex mirror are positive.
Sign Conventions for reflection by spherical mirrors
(1) All distance are measured from the pole of a spherical mirror.
(2) Distance measured in the direction of incident light are taken as positive. Distance measured in the direction opposite to that of the incident light are taken negative.
(3) The upward distance perpendicular to the principal axis are taken as positive, while the downward distance perpendicular to the principal axis are taken as negative.
Radius of curvature plane mirror = ( infinite)
Focal length of a plane mirror =
Mirror Formula : The relation between u, v, and focal length (f) of a spherical mirror is known as mirror formula.
That is
Linear magnification : Linear magnification produced by a mirror is defined as the ratio of the size
( or height) of the image to the size of the object . It is denoted by m.
That is
Power of mirror (P) = =
Linear magnification produced by a plane mirror = + 1.
Refraction of light: The bending of light rays when they pass obsessively from one medium to the other medium is called refraction of light .
A transparent medium through which light travels fast is known as optically rarer medium.
A transparent medium through which light travels slow is known as optically denser medium.
Laws of refraction
(i) The incident ray, the refracted ray and the normal to the surface separating two media all lie in the same plane.
(ii) The ratio of the sine of the incident angle (i) to the sine of the refracted angle (r) is constant
i.e. sin i/ sin r = constant
This constant is known as the refractive index of second medium w.r.t the first medium.
Absolute refractive index of a medium is defined as the ratio of the speed of light in vacuum (c) to the speed of light in the medium (v)
i.e. n = c / v
Relative refractive index of medium. 2 w.r.t. the medium 1 is defined as the ratio of the speed of light in medium 1 (v1) to the speed of light in medium 2 (v2).
i.e. n21= v2 / v1
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8min
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CHEMISTRY - Structure of Atom Part 1 - Lecture 1
STRUCTURE OF ATOM - In this chapter we will learn the composition atom and how molecules are made up with atoms. These are the topics (Electrons, protons and neutrons, valency, chemical formula of common compounds. Isotopes and Isobars) that will be discussed in the lectures.
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36min
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CHEMISTRY - Structure of Atom Part 2 - Lecture 2
STRUCTURE OF ATOM - In this chapter we will learn the composition atom and how molecules are made up with atoms. These are the topics (Electrons, protons and neutrons, valency, chemical formula of common compounds. Isotopes and Isobars) that will be discussed in the lectures.
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40min
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CHEMISTRY - Structure of Atom Part 3 - Lecture 3
STRUCTURE OF ATOM - In this chapter we will learn the composition atom and how molecules are made up with atoms. These are the topics (Electrons, protons and neutrons, valency, chemical formula of common compounds. Isotopes and Isobars) that will be discussed in the lectures.
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35min
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CHEMISTRY - Structure of Atom Part 4 - Lecture 4
STRUCTURE OF ATOM - In this chapter we will learn the composition atom and how molecules are made up with atoms. These are the topics (Electrons, protons and neutrons, valency, chemical formula of common compounds. Isotopes and Isobars) that will be discussed in the lectures.
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18min
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CHEMISTRY - CHEMICAL REACTIONS PART -1 LECTURE - 5
CHEMICAL REACTIONS - In this Chapter we will learn the following topics which includes Chemical equation, Balanced chemical equation, implications of a balanced chemical equation, types of chemical reactions: combination, decomposition, displacement, double displacement, precipitation, neutralization, oxidation and reduction.
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26min
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CHEMISTRY - CHEMICAL REACTIONS PART -2 LECTURE -6
CHEMICAL REACTIONS - In this Chapter we will learn the following topics which includes Chemical equation, Balanced chemical equation, implications of a balanced chemical equation, types of chemical reactions: combination, decomposition, displacement, double displacement, precipitation, neutralization, oxidation and reduction.
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29min
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CHEMISTRY - CHEMICAL REACTIONS MCQ PART -3 LECTURE -7
CHEMICAL REACTIONS - In this Chapter we will learn the following topics which includes Chemical equation, Balanced chemical equation, implications of a balanced chemical equation, types of chemical reactions: combination, decomposition, displacement, double displacement, precipitation, neutralization, oxidation and reduction.
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14min
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CHEMISTRY - ACIDS , BASES AND SALTS Part 1 - Lecture 8
ACIDS , BASES AND SALTS - In this topic we will learn what is acid and base and their uses. The lectures will cover the following topic which includes the definitions of acids and bases in terms of furnishing of H+ and OH– ions, General properties, examples and uses, concept of pH scale (Definition relating to logarithm not required), importance of pH in everyday life; preparation and uses of Sodium Hydroxide, Bleaching powder, Baking soda, Washing soda and Plaster of Paris
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42min
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CHEMISTRY - ACIDS , BASES AND SALTS Part 2 - Lecture 9
ACIDS , BASES AND SALTS - In this topic we will learn what is acid and base and their uses. The lectures will cover the following topic which includes the definitions of acids and bases in terms of furnishing of H+ and OH– ions, General properties, examples and uses, concept of pH scale (Definition relating to logarithm not required), importance of pH in everyday life; preparation and uses of Sodium Hydroxide, Bleaching powder, Baking soda, Washing soda and Plaster of Paris
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60min
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CHEMISTRY - ACIDS , BASES AND SALTS MCQ Part 3 - Lecture 10
ACIDS , BASES AND SALTS - In this topic we will learn what is acid and base and their uses. The lectures will cover the following topic which includes the definitions of acids and bases in terms of furnishing of H+ and OH– ions, General properties, examples and uses, concept of pH scale (Definition relating to logarithm not required), importance of pH in everyday life; preparation and uses of Sodium Hydroxide, Bleaching powder, Baking soda, Washing soda and Plaster of Paris
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16min
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CHEMISTRY - METALS AND NON METALS Part 1 - Lecture 11
METALS AND NON METALS - In this topic we will discuss the following topics which includes Properties of metals and non-metals; Reactivity series; Formation and properties of ionic compounds; Basic metallurgical processes; Corrosion and its prevention.
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22min
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CHEMISTRY - METALS AND NON METALS Part 2 - Lecture 12
METALS AND NON METALS - In this topic we will discuss the following topics which includes Properties of metals and non-metals; Reactivity series; Formation and properties of ionic compounds; Basic metallurgical processes; Corrosion and its prevention.
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30min
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