ASSIGNMENT
SESSION- 2017-18
CLASS: IX
SUBJECT: PHYSICS
CHAPTER-1: MOTION
1.What is meant by the statement ‘Rest and motion are relative terms’? Give example to show it.
2.Explain whether the walls of a classroom are at rest or in motion.
3.Define scalar and vector quantities.
4.Identify the following as scalar or vector quantities:-mass, velocity, speed, length, distance,
displacement, temperature, force, weight, power, work and energy.
5.The school of a boy from his home is 1 km to the east. When he reaches back home, he says
that he had traveled 2 km distance but his displacement is zero. Justify your answer.
6.Under what condition, the average speed is equal to the magnitude of the average velocity.
7.Can the average speed of a moving body be zero?
8.Can the average velocity of a moving body be zero? State examples.
9.A car covers a distance of 5 km in 20 mins. Find the velocity of the car in (a) km/min(b) m/s(c) m/min
(d) km/hr.
10.a train is moving with a velocity of 45km/hr. calculate the distance traveled by it in 1 hr, 1 min,
1second.
11.An object P is moving with a constant velocity for 5 mins. Another object Q is moving with
changing velocity for 5 mins. Out of these two objects, which one has acceleration? Explain.
12.Can an object be accelerated if it is moving with constant speed? If yes, explain giving examples.
13.(i) When do you say that an object has positive acceleration? (ii) When do you say that an object has
negative acceleration?
14.State which of the following situations are possible and give an example of each of these:-(a)a body
moving with constant acceleration but with zero velocity.(b)A body moving horizontally with
acceleration in vertical direction.(c)A body moving with a constant speed in an accelerated motion.
15.What is a reference point?
16.Name the 2 physical quantities which can be obtained from velocity-time graph.
17.An electric train is moving with a velocity of 120km/hr. how much distance will it cover in 30 sec?
18.Give differences between linear motion and circular motion.
19.Velocity time graph of a body is shown in the figure. What are initial and final velocities of the body?
20.A body moves around the sun with constant speed in circular path. Is the motion of the body uniform
or accelerated?
21.Name the physical quantity which remains constant during uniform circular motion.
22.Name the physical quantity which changes during uniform circular motion
23. An object is moving up an inclined plan. Its velocity changes from 15m/s to 10m/s in two
seconds. What is its acceleration? (ans. -2.5m/s2)
24. A particle moving with an initial velocity of 5m/s is subjected to a uniform acceleration of 2.5m/s2. Find the displacement in the next 4 sec. (ans. 0)
25. A car covers 30km at a uniform speed of 30km/hr. what should be its speed for the next
90km if the average speed for the entire journey is 60km/h? (ans. 90km/hr)
26. A boy runs for 10 min. at a uniform speed of 9km/h. At what speed should he run for the next
20 min. so that the average speed comes 12km/hr? (ans.13.5km/h)
CHAPTER-: FORCE AND LAWS OF MOTION
Q. 1. How much force is needed to accelerate a trolley of mass 20g through 1 m/s2.
Q. 2. A force of 100N acts on a mass of 25 kg for 5 s .What velocity does it generate?
Q. 3. A bullet leaves a rifle with a velocity of 100m/s and the rifle of mass 2.5 kg recoils with a
velocity of 1m/s. Find the mass of the bullet?
Q. 4. A certain force acting on a mass of 15kg for 3s, gives it a velocity of 2m/s. Find the
magnitude of force.
Q. 5. A cricket ball of mass 0.15 kg is moving with a velocity of 1.2m/s . Find the impulse on the
ball and average force applied by the player if he is able to stop the ball in 0.18s.
Q. 6. A motor car of mass 200kg is moving with a certain velocity . It is brought to rest by the application
of brakes, within a distance o f 20m when the average resistance being offered to it is 500N.What was
the velocity of the motor car?
Q. 7. A body of mass 0.5kg undergoes a change of velocity of 4cm/s in 4s What is the force
acting on it?
Q. 8. A force of 8N acting on an 8kg mass for 4s provides its some velocity. Calculate the velocity
Q. 9. What would be the weight of a body of mass 50kg on the surface of the moon, where g = 1.6m/s2
what would be its mass?
Q. 10. A boy jumps a distance of 2m on the surface of the earth. What distance will he jump on the
surface of the moon where g is 1/6th of the value on the surface of the earth?
Q. 11. Two bodies of mass 1kg and 2 kg moving in the direction opposite to each other with a speed
5m/s collide. Calculate the total momentum of the system before collision.
Q. 12. A bullet of mass 15g leaves the barrel of a gun with a velocity of 120m/s.The gun recoils with a
velocity of 1m/s. Find the mass of the gun.
Q. 13. A force of 3N acts on a mass of 0.5kg at rest for 10s. Find the final velocity and the momentum of
the body after 10s.
Q. 14. A force of 80N acting on a certain mass for 3s gives it a velocity of 6m/s. find the mass of the body
if the body was initially at rest.
THEORETICAL QUESTIONS:
Q1. Define force and its si unit?
Q 2. Distinguish between balanced and unbalanced force?
Q3. State three laws of motion?
Q 4. What is inertia? Is inertia vector quantity. Justify?
Q5. What is impulse? Prove that impulse is equal to change in momentum?
Q. 6. Define momentum and prove that f = ma
7. Is it possible that a body keeps on moving with uniform velocity with? If yes give reason also name
scientist who explained this statement?
Q 8. Why a person sitting in bus fall forward when moving bus suddenly stops?
Q9. Why people sitting in bus fall backward when bus suddenly starts?
Q10. Why dust fall on beating carpet with stick?
Q11. Why leaves fall when we are shacking branch of tree?
Q12. Why an athlete runs certain distance before taking long jump?
Q13. When bus takes u turn, passengers sitting inside thrown a side. Why?
Q14. Explain why it is difficult for a fireman to hold a hose, which ejects large amount of water at a
high velocity.
Q15. How a karate player can break a pile of tiles with a single blow of his hand?
Q.16. Why does a bullet when fired against a glass window pane make a hole in it, and the glass pane
will smash it?
Q.17. Why is it advised to tie a rope on the luggage while you travel by the bus?
Q18.Why vehicles are provided with shocker?
Q19. Why does a bicycle begin to slow down when we stop pedaling?
Q20. State and verify the law of conservation of momentum?
Q21. When we hit at the bottom of the pile of carom coins, other coins fall vertically on the carom board
why?
Q22. Two balls A and B of masses 'm' and '2 m' are in motion with velocities '2 v' and 'v' respectively.
Compare
(i) their inertia
(ii) their momentum and (iii) the force needed to stop them in the same time
CHAPTER-GRAVITATION
1.Question: Two balls of different masses are thrown vertically upwards with same initial speed.
Which one of them will rise to the greater height?
2. The earth and the moon are attracted to each other by gravitational force. Does the earth attract
the moon with a force that is greater or smaller or the same as the force with which the moon attracts
the earth? Why?
Q1 Which force keep the moon going around the Earth. Who provides this force? What would have
happened in the absence of such a force?
Q2 A falling apple attracted towards the earth. Then why don’t we see the earth moving towards the
apple?
Q3 Why is the Law of Gravitation called Universal law of gravitation?
Q4 Object towards the earth is accelerated or not. Explain?
Q5 Weight of an object at a given place can be the measure of its mass. Comment.
Q6 Moon exerts lesser force of attraction on an object as compared to that of earth. Comment.
Q7 Give reasons:
(a)A camel can run in a desert easily as compared to horse.
(b)A army tank weighing more than a thousand tone rests upon a continuous chain.
(c)A truck or motorbus has much wider tires.
(d)Cutting tools have sharper edges.
(e)Buildings have broad foundations
(f)Dams have broader walls at the bottom.
(g)A cork floats while a nail sinks in water
(h)A body loses its weight when dipped in water
Q8. Name the factor on which the density of the fluid depends
Q9 the gravitational force between sun and Jupiter is approximately 4x10
23N. if the mass of the sun= 1.99x1030kg, the mean distance of the Jupiter from the sun is 7.8x1011m
find the mass of Jupiter.
Q10 A particle is Thrown up vertically with a velocity of 50m/s.What will be the velocity at the highest
point of its journey? How high the particle would rise? What time would it take to reach the highest
point?
Q11 A ball is dropped from the top of a tower 40m high. What is its velocity when it has covered 20m?
What would be its velocity when it hits the ground?
Q12 an object is released from a height.(a)Find its speed at(1) t= 1s, (2) t=2s, (3) t= 3s.(b)Find the
distance traveled at (1) t=1s, (2) t=2s (3) t=3s.
Q13 a body drops from the edge of the roof. It passes a 2m high window in 0.1s. How far is the roof
above the window?
Q14. Two friends decide to calculate the height of a high-rise building. They match the timings of their
watch. One friend goes to the top storey and one stands on the ground. The friend at the top story
drops a stone and notes the time. The friend standing on the ground notes the time when the stone
reaches the ground. They meet and find that the time taken by the stone to reach the ground is 6sec.
Find the height of the high rise building.
Q15. Weight of an object is 294n on the surface of the earth. What is the weight at a height of 200km
from the surface of the earth? Radius of the earth= 6400km.
Q16 A body is thrown upwards .What is the direction of g when
the body is (1)moving upward (2) at the topmost point of its journey (3) falling down
Q17. Find thevalue of acceleration due to gravity at a height of (a) 6400km from the surface of the earth.
Radius of the earth is 6400km.
Q18. What is the weight of a person whose mass is 50kg.
Q19.The mass of a man is 60kg. How muchwill he weigh on the (1) earth (2) moon?
Q20.Ammanweighs 81.5n on the moon. If the acceleration due to gravity on the moon is 1.63m/s2,
find the mass of the man and his weight on the earth
GRAVITATION
1. Pascal is a unit of
a) pressure
b) force
c) linear momentum
2. The buoyant force on a body acts in a
a) vertically downward direction
b) vertically upward direction
c) horizontal direction
d) direction between the horizontal and the vertical
3. The force acting normally on a surface is called
a) pressure
b) Thrust
c) Force
d) Balanced
d) energy
Section B
4. Define pressure at a point.
5.State Archimedes principle.
6. Why is it easier to swim in sea water than in fresh water?
7. Does a liquid press an immersed body from all sides?
8. A body of volume 50 cm3 is completely immersed in water. Find the force of buoyancy on it.
9. A block weighing 1 kg is in the shape of a cube of length 10 cm. It is kept on a horizontal table. Find
the pressure on the portion of the table where the block is kept.
10. A bottle weighs 30 g when empty, 53.4 g when filled with a liquid and 48 g when filled with water.
Calculate the density of the liquid. Given, density of water at 40C = 1000 kg/m3.
11. A metallic sphere of radius 2.0 cm is completely dipped in water. Find the force of buoyancy on it.
A cubical block of copper is dipped completely in water. Each edge of the block is 1cm in length. Find the
buoyant force acting on the cube.
Chapter: Work and Energy
Section A
1. Newton-metre is the unit of
a) Power
b) Work
c) Momentum
d)
Gravitational
Intensity
2. A body is moved through a distance of 3 m in the following different ways. In which case
is the maximum work done?
a) When pushed over an inclined plane
b) When lifted vertically upward
c) When pushed over smooth rollers
d) When pushed on a plane
horizontal surface.
3. No work is done when
a) a donkey is carrying a load on its back
b) on engine is pulling a train
c) a sail boat is moving due to wind energy
d) a wind mill is lifting water from a
well.
4. What is the work done by a boy in pushing a book with a force of 5 N and displacing it
through 20 cm along the push?
a) 1J
b) 2J
c) 1.5 J
d) 3J
5. The kinetic energy of a body depends
a) on its mass only
b) on its speed only
c) on its mass as well as on its speed d) neither on its mass nor on its speed.
6. A body of mass 10 kg is dropped from a height of 2m. If g is taken to be 10 m/s2, the
kinetic energy of the body just before striking the ground will be
a) 400J
b) 4J
c) 40J
d)
none
7. A ball is thrown upwards from a point A. it reaches up to the highest point B and returns
at the same point. Which of the following statement is correct
a) Kinetic energy at A = kinetic energy at B b) Potential energy at A = potential energy
at B
c) Potential energy at B = kinetic energy at B
d) Potential energy at B = kinetic
energy at A
8. When the speed of a particle is doubled, its kinetic energy
a) remains the same
b) gets doubled
c) becomes half
d) becomes 4
times.
9. When the speed of a body is doubled, the ratio of kinetic energy to its momentum.
a) gets doubled
b) remains the same
c) becomes half
d) becomes 4
times.
10. Two bodies of unequal masses are dropped from a cliff. At any instant, they have equal
a) momentum b) acceleration
c) kinetic energy
d) potential energy.
11. A body is dropped form a certain height above the ground when it is half way down, it
possesses
a) Only kinetic energy
b) Only potential energy
c) Both kinetic and potential d) no energy at all energy
12. A flying aeroplane possesses
a) Only P.E.
b) Only K. E.
c) both potential and kinetic energy d) Neither potential nor kinetic energy.
13. In which of the following cases is the potential energy of a spring minimum?
a. When it is compressed
b. When it is extended
c. When it is at its natural length
d. When it is at its natural length but kept at a height above ground.
14. When a body roller down an inclined plane,
a) Only K.E
b) only P.E
c) both K.E and P.E
d) neither K.E. nor
P.E.
15. kWh is unit of
.a) Power
b) momentum
c) impulse
d) energy
16. The unit of power is
a) Watt
b) joule
c) Newton
d) kg
17. No. of joules in kWh is
a) 36×103
b) 36×10-4
c) 36×102
d) 3.6 ×106
Section B
1. Define work. Is it scalar or vector quantity?
2. What is the condition for a force to do work on a body?
3. A man is rowing a boat upstream, but his boat remains at rest with respect to the
shore. Is he doing any work?
4. Give an example where the displacement of a particle is in the direction opposite to
force acting on this particle.
5. What happens to the work done when the displacement of a body is at right angles
to the direction of force acting on it? Explain your answer.
6. A ball of mass 1 kg thrown upwards, reaches a maximum height of 5 m. Calculate the
work done by the force of gravity during this vertical displacement.
7. A person pulls a body on a horizontal surface by applying a force of 5 N at an angle of
30º with the horizontal. Find the work done by this force in displacing the body
through 2 m. (cos 30º =√3/2)
8. A horizontal force of 50 N displaces on object of mass 100 kg. Calculate the distance
moved and work done by the force in 8 seconds.
9. A car of mass 2500 kg travelling at a speed of 40 m/s stops after covering a distance
of 50 m when brakes are applied. Calculate (a) the force exerted on it by the brakes
(b) work done by brakes.
10. Differentiate between work, power and energy. Also state their S.I. units.
11. Define kinetic energy. Give one example also.
12. By what factor does the kinetic energy of a particle of mass m increase if the speed is
increased by factor of 3?
13. Does the kinetic energy of a body depend on its direction of motion?
14. By how much will the kinetic energy of a body increase if
Speed is doubled ii) Speed is halved.
15. Deduce the formula of kinetic energy of a body moving with velocity, v
16. A ball of mass 0.5 kg slows down from a speed of 5m/s to that of 3m/s. Calculate
change in kinetic energy of the ball.
17. A block is thrown upwards with a K.E. of 2J. If it goes up to a maximum height of 2m,
find the mass of the block.
18. The mass of a ball A is double the mass of Ball B. The ball A moves at half the speed
of ball B. Calculate the ratio of K.E. of A to K. E. of B.
19. A body A of mass 3 kg and body B of mass 2 kg are dropped simultaneously from a
height of 14.9 m. Calculate ratio of the kinetic energy when they just touches the
earth
20. Differentiate between work, power and energy. Also state their SI units.
21. Define potential energy. Give one example.
22. Which of the following are examples of potential energy?
a) A boy at the top of a slide b) a stretched catapult
c) a hot iron d) a stretched bow heir momenta e) their kinetic energies
e) the arrow in stretched bow
23. State the principle of conservation of energy.
24. A ball is dropped from a height H. When it reached the ground, its velocity is 50 m/s.
Find height H.
25. A body of mass 100 kg is lifted up by 10 m. Find Amount of work done ,Potential
energy of the body at that height (value of g = 10 m/s2)
26. A boy weighing 40 kg carries a box weighing 20 kg to the top of building 15 m high in
25 sec. Calculate the power. (g = 10 m/s2)
27. Two persons do the same amount of work in 10s and 20 s respectively. What is the
ratio of the power used by first person to that by second person?
28. Calculate the power developed by a 110 kg mass climbing up a vertical staircase at
the rate of 2m/s. (g= 9.8 m/s2) H.O.T.S. Questions
29. A lorry and a car moving with same kinetic energy are brought to rest by application
of brakes which provide equal retarding forces. Which one
CHAPTER: SOUND
Section A
1. Sound is a type of
a) Energy
b) force
c) charge
d) matter of them will come to rest in a shorter
distance?
2. Sound waves can travel through
a) Gases only
b) vacuum only
c) gases and liquids only
d) Solids, liquids and gases.
3. Sound waves are
a) longitudinal
b) transverse
c) both a) & (b)
d) None of the above
4. Sound waves can be
a) Reflected
b) Absorbed
c) Diffracted
d) All of the above
5. Speed of sound waves in water is about
a) 332 m/s
b) 1440 m/s
c) 5000 m/s
d) 15000 m/s
6. Speed of sound in ordinary air
a) is less than Carbon dioxide
b) greater than CO2
c) equal to CO2
d) None of these
7. In which of the following mediums will sound travel fastest
a) liquid
b) solid
c) gas
d) vacuum.
8. Hertz is a unit of
a) frequency
b) wave speed
c) displacement
d) wavelength
9. The upper frequency limit of the audible range of human hearing is about
a) 20 KHz
b) 2000 Hz
c) 2 KHz
d) 200000 Hz
10. Ultrasonic waves have frequencies
a) below 20 Hz
b) between 20 Hz and 200000 Hz
c) above 20000 Hz
d) no lower or upper limit of frequency.
11. Infrasonic waves have frequencies
a) below 20 Hz
b) between 20 Hz and 20000 Hz
c) above 20000 Hz
d) no upper or lower limit of frequencies
12. Ultrasound is an application of
a) infrasonic waves
b) ultrasonic waves
c) sound waves
d) light waves
13. In order to hear an echo, time gap between original sound and reflected sound is
a) equal to 1/10 and
b) greater than 1/10 and
c) both (a) and (b)
d) none of the above
14. The properties of ultrasound that make it useful are:
a) high power and high speed
b) Good directionality and high power
c) High speed and frequency
d) Good directionality and ability to move around
objects.
Section B
1. What type of waves are produced in air when a bell rings?
2. How does sound from a sound producing body travel through air to reach our ears?
3. When we open a gas tap for a few seconds, the sound of escaping gas is heard first but smell
of
gas comes later why?
4. Describe an experiment to show that sound is not transmitted through vacuum.
5. Define the following terms
a) echo b) amplitude c) wavelength d) frequency
e) pitch f) loudness g) time period
6. Distinguish between echo and reverberation.
7. A stone is dropped from the top of a tower 300m high splashes into water of a pond near
the
base of the tower. When is splash heard at the top?
Given, Speed of sound in air = 340 m/s and g = 9.8 m/s2
8. If 5 seconds elapse between a lightning flash and the clap of thunder how far away is the
storm?
Speed of sound in air = 332 m/s
9.A person makes a loud sound and hears the echo of this sound 1.2 s later. Calculate how far
the
person is from the object causing the echo. Assume speed of sound is 332 m/s
10. Describe the relation between velocity, wavelength and frequency?
11. What is the difference between the terms „ultrasonic‟ and „supersonic‟?
12. Name an animal which navigates and finds food by echo location.
13. How are bats able to fly at night without colliding with other objects
14. Name the principle on which a megaphone works? Explain that principle.
15. Give various uses of ultrasound.
16. Given below is the structure of ear. Label its various parts.
17. A bat emits ultrasonic sound of frequency 100 KHz in air. If this sound meets a water
surface, what is the wavelength of
(a) The reflected sound (b) transmitted sound?
(Speed of Sound in air = 340 m/s)
18. A hospital uses an ultrasonic scanner to locate tumours in a tissue what is the wavelength of
sound in a tissue in which speed of sound is 1.7 km/s? The operating frequency of scanner is 4.2
MHz.
19. A tuning fork makes 284 vibrations per second in air. Compute the wavelength of the tone
emitted.
Given speed of sound = 330 m/s.
H.O.T.S. Questions
Q.1 After the snow fall, why does it seem particularly quite?
Q.2 Why do empty rooms sound hollow?
Q.3 Which travels faster: a radio signal or sound in air?
Q.4 A child watching Dussehra celebrations from a distance sees the effigy of Ravana burst
into flames and hears the explosion associated with it 2 s after that. How far was he from
the effigy of the speed of sound in air that night was 335 m/s
ASSIGNMENT
SESSION- 2017-18
CLASS: X
SUBJECT: PHYSICS
CHAPTER-1:ELECTRICITY
One mark questions
1. Define the term “electric current”.
2. Define the term ‘resistivity’ of a material.
3. How is a Voltmeter connected in the circuit to measure the potential difference between two points?
4. You have two metallic wires of resistances 6 ohm and 3 ohm. How will you connect these wires to get
the effective resistance of 2 ohm?
5. If the distance between two electric charges is doubled, how much will the force exerting between
them change to?
Two marks questions
6. State Ohm’s law. “The resistance of a conductor is 1Ω.” What is meant by this statement?
7. Why are coils of electric toaster made of an alloy rather than a pure metal?
8. Why is the series arrangement not used for domestic circuits?
9. A wire of resistivity ‘r’ is stretched to double its length. How does it affect the (a) resistance (b)
resistivity?
10. Write two points of difference between direct and alternate current
11. An electric geyser has the rating 2000W-220 V marked on it. What should be the minimum current
rating (in whole number) of the fuse – wire to be used?
12. An electric lamp is marked 100 W, 220 V. It is used for 5 hour daily. Calculate (i) its resistance while
glowing (ii) energy consumed in kWh per day.
13. A bulb is rated at 5.0 volt, 100 mA. Calculated its (i) power (ii) resistance.
14. A wire of resistance ‘R’ is stretched by 50%. What will be percentage change in it’s resistance?
15. The resistance of 100 W bulb is less than resistance of 40 W bulb. Explain the reason. 3 marks
questions
16. Derive the equation for resultant resistance of Resistors in series
17. How much work is done in moving a charge of 3 coulumb from a point at the volts 115 to a point at
125 volts?[ 30j]
18. A heater wire whose power is 4KW is connected to 220 V source calculate:(i) Electric current in the circuit (ii) Resistance of heater (iii) Energy consumed in 2 hours.
19. For a heater rated at 4 kW and 220 V, calculate (a) the current, b) the resistance of the heater, C) the
energy consumed in 2 hours, and d) the cost if 1 kWh is priced at Rs. 4.60.
20. An electric motor takes 5 amperes current from a 220 volt supply line. Calculate the power of the
motor arid electrical energy consumed by it in 2 hours.
21. Which uses more energy: a 250 W TV set in 1 hour or a 1200 W Toaster in 10 minutes?
22. An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across
the two wires of 220 V supply line if the maximum current which can be drawn is 5 A.
23. How much work is done in moving a charge of 2 coulombs from a point at 118 volts to a point at 128
volts?
24. What possible values of resultant resistance one can get by combining two resistances, one of value
2 ohm and the other 6 ohm?
25. If 3 resistances of 3 ohm each are connected in parallel, what will be their total resistance?
26. If five resistances, each of value 0.2 ohm, are connected in series, what will be the resultant
resistance?
27. Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in
series. What is the total resistance?
28. An electric bulb of resistance 20 and a resistance wire of 4 are connected in series with a 6 V battery.
Draw the circuit diagram and calculate (i)the total resistance of the circuit.(ii) Current through the
circuit. (iii)Potential difference across the electric bulb.(iv)Potential difference across the resistance
wire.
29. How will you connect three resistors of 2 ohm, 3 ohm and 5 ohm respectively so as to obtain a
resultant resistance of 2.5 ohm? Draw the diagram to show the arrangement.
30. How will you connect three resistors of resistances 2ohm, 3 ohm and 6 ohm to obtain a total
resistance of: (a) 4 ohm, and (b) 1 ohm?
31. A wire of resistance R is cut into five equal pieces. These five pieces of wire are then connected in
parallel. If the resultant resistance of this combination be R then the ratio of resultant to the original will
be?
32. A copper wire has a diameter of 0.5 mm and resistivity of 1.6 x 10 m.
1. What will be the length of this wire to make its resistance 10 2ohm?
2. How much does the resistance change if the diameter is doubled?
33. An electric heater which is connected to a 220 V supply line has two resistance coils A and B of 24
resistances each. These coils can be used separately (one at a time), in series or in parallel. Calculate the
current drawn when
1. Only one coil A is used.
2. Coils A and B are used in series.
3. Coils A and B are used in parallel.
34. If the length of a wire is doubled by taking more of wire, what happens to its resistance?
35. How does the resistance of a wire change when
1. Its length is tripled?
2. Its diameter is tripled?
3. Its material is changed to one whose resistivity is three times?
36. How much energy is given to each coulomb of charge passing through a 6 V battery?
37. The potential difference between the terminals of an electric iron is 240 V and the current is 5.0 A.
What is the resistance of the electric iron?
38. A potential difference of 20 volts is applied across the ends of a resistance of 5 ohms. What current
will flow in the resistance?
39. A resistance of 20 ohms has a current of 2 amperes flowing in it. What potential difference is there
between its ends?
40. A current of 5 amperes flows through a wire whose ends are at a potential difference of 3 volts.
Calculate the resistance of the wire.
41. The resistance of an electric lamp filament is 230 ohms. The lamp is switched on when the line
voltage is 115 volts. What is the current in the lamp circuit?
42. What is the potential difference between the ends of a conductor of 16 ohm resistance, when a
current of 1.5 A flows through it?
43. Calculate the work done in moving a charge of 4 coulombs from a point at 220 volts to another point
at 230 volts.
44. What is the potential difference between the terminals of a battery if 250 joules of work is required
to transfer 20 coulombs of charge from one terminal of the battery to the other?
45. How much work is done in moving a charge of 2 C across two points having a potential difference of
12 V?
46. An electric bulb draws a current of 0.25 A for 20 minutes. Calculate the amount of electric charge
that flows through the circuit.
47. A radio set draws a current of 0.36 A for 15 minutes. Calculate the amount of electric charge that
flows through the circuit.
48. Potential difference between two points of a wire carrying 2 ampere current is 0.1 volt. Calculate the
resistance between these points.
49. A simple electric circuit has a 24 V battery and a resistor of 60 ohms. What will be the current in the
circuit? The resistance of the connecting wires is negligible.
50. A wire of resistance R is cut into five equal pieces. These five pieces of wire are then connected in
parallel. If the resultant resistance of this combination be R then the ratio of resultant to the original will
be?
Q51. Study the following data and write which set of value should be rejected so that ohm’s law holds
good for the remaining set of values. Draw the graph and find out the mean resistance (3)
V(volts)
I(A)
2.5
0.1
5.0
0.2
10.0
0.3
15.0
0.6
20.0
0.8
25.0
1.0
52. (a) Which has more resistance: 100W bulb or 60W bulb?
(b) A wire of resistance 5W is bent in the form of a closed circle. What is the effective resistance
between the two points at the end of any diameter of the circle?
53. Two wires A and B are of equal lengths, different cross-sectional areas and made of the same metal.
(i) Name the property which is same for both the wires.
(ii) Name the property which is different for both the wires.
(iii) If the resistance of wire A is four times the resistance of wire B, calculate
(a)the ratio of the cross-sectional areas of the wires.
(b)the ratio of the radii of the wires.
54. Drift speed is the term used to describe the flow of current through a conductor. Does it represent
the speed of the current or its strength?
55. A resistor of 8ohm is connected in parallel with another resistor X. The resultant resistance of the
combination is 4.8 ohm . What is the value of X?
56. How will you connect three resistors of 2 ohm , 3 ohm , 5 ohm respectively so as to obtain a
resultant resistance of 2.5 ohm ? Draw the diagram to show arrangement.
57. A wire of resistance 5 ohm is bent in form of closed circle. What is the effective resistance between
the two points at ends of any diameter of circle?
CHAPTER:- MAGNETIC EFFECT OF CURRENT:
1. A proton enters in a straight line in a uniform magnetic field along the field direction. How
will its path and velocity change?
2. A positive charge is moving vertically upwards in magnetic field towards south. In which
direction will it be deflected?
3. Free electrons always keep on moving in the conductor. Even then no magnetic force acts
on them in a magnetic field. Why?
4. What is the nature of the magnetic field generated by a current carrying straight conductor?
5. An electron and proton enter a uniform magnetic field perpendicular to the direction of the
field with same velocity. Will the force on them be same?
6. Under what conditions electron moving in the uniform magnetic field experiences maximum
force?
7. An electron is projected with its velocity in the direction of the magnetic field. Will its motion
be affected?
8. What is the pattern of the magnetic field lines around a straight conductor carrying current?
9. If the current is flowing in the direction of advancement of screw, then what is the direction
of magnetic field lines?
10. How can you say that the magnetic field is uniform inside the solenoid.
11. According to Flemings right hand rule, which part of right hand
indicate the movement of conductor?
12. In which position the force on conductor is maximum when it is placed in uniform magnetic
field?
13. A current through a horizontal power line flows in north to south direction. What is the
direction of magnetic field (i)at a point directly below it and (ii)at a point directly above it?
14. Consider a circular wire lying in the plane of the table and the direction of current in it is
anticlockwise.(i) Draw the magnetic field lines produced around it.
(ii) Why does magnetic field at the center of current carrying circular loop appear straight?
Explain with diagram.
15. If we place a compass needle near straight conductor carrying current
(a)What happens to the deflection of the compass needle if the direction of current is reversed
.
(b)What change will you notice in the compass needle if it is moved away from conductor but
the current through the conductor remains the same?
CHAPTER-:SOURSES OF ENERGY
1.
2.
3.
4.
5.
6.
.What is energy?
What should be the characteristics of a source of energy?
What are renewable and non-renewable sources of energy? Give examples of each.
Give two advantages and 2 disadvantages, each of renewable and non-renewable sources of energy.
. Name a gaseous fossil fuel.
What are the limitations of extracting energy from (a) the wind (b) the waves (c) the tides?
7. Name two indirect ways of using solar energy.
8. What are the environmental consequences of the increasing demand for energy? What steps would
you suggest to reduce energy consumption?
9. Name two indirect ways of using solar energy.
10. Give the transformation of energy (sequence) taking place in (a) Thermal power plant (b) hydro
power plant (c) solar cel
11. Give advantages and disadvantages of constructing dams.
12. What is the use of black painted surface in solar heating devises.
13. Why are bio gas plants considered to be boon to the farmers? Give reason.
14. Hydroelectricity generated at a dam may be considered another form of solar energy. Why?
15. How is the slurry left over after the generation of biogas in biogas plant used?
16. . Why is charcoal considered to be a better fuel than wood?
17. Why a solar cooker cannot be used for frying or making chapattis?
18. In parabolic reflector type coolers, even temperature up to 1800C- 2000C can be
attained. How?
19. Modern chulahs are more efficient than traditional chulahs. Why?
20. How is hydro energy converted into electrical energy?
21. Explain, why only a part of the solar energy that strikes the upper regions of
atmosphere reaches the surface of the earth?
22. (i) write the value of solar constant of sun. (ii) what type of mirror is used in Box Type Solar
cooker? (iii) why it is difficult to use hydrogen as a source of energy? (iv)what is the maximum
temperature attained in a concave reflector type solar cooker? (v)Fossil fuels are classified as
non-renewable source of energy. Explain why.
23. (a) Why is solar cooker box covered with a plane glass plate? (b) Why is the energy of water
flowing in a river considered to be an indirect form of solar energy? (c) Write one advantage of
nuclear fission reaction.
24. (a) State one limitation of solar energy available from solar cells. (b) What is the minimum
wind velocity required to obtain useful energy with a wind will ? (c) Define the term ‘nuclear
fission’.
25. Why are many thermal power plants set up near coal or oil fie lds?
26. what is a solar power plant? Name one such plant in our Country.
27.what is geothermal energy? What are its advantages?
LIGHT REFLECTION AND REFRACTTION
Section – A
Q.1. A real and diminished image of an object can be obtained by,
(i) Plane Mirror
(ii) Concave Mirror
(iii) Convex Mirror
(iv) Both Concave & Convex Mirrors
Q.2. The relation between f and R in case of a concave mirror is,
(i) f = 2R
(ii) f = 2/R
(iii) f = 1/R
(iv) f = R/2
Q.3. Image formed by reflection from a convex mirror is,
(i) Real only
(ii) Virtual only (iii) Both real & virtual
(iv) Neither real nor virtual
Q.4. Which of the following letter doesn‟t show lateral inversion,
(i) N
(ii) Q
(iii) P
(iv) O
Q.5. Linear magnification of a plane mirror is,
(i) Always positive
(ii) Always negative
(iii) Both +ive and -ive
(iv) Depends upon
position of the object
Q.6. Mirror formula is applicable to,
(i) Plane mirrors only
(ii) Spherical mirror only
(iii) Both plane and spherical mirror
(iv) Neither plane nor spherical
Q.7. Magnification of mirror is + . The type of mirror is,
(i) Concave
(ii) Plane
(iii) Convex
(iv) Combination of all
Q.8. When an object placed in front of a convex mirror is moved away from it, the image –
(i) Also moves away from focus
(ii) Moves closer to focus
(iii) Becomes larger and larger
(iv) Becomes real and inverted
Q.9. Plane mirror is a part of sphere of radius
(i) Zero
(ii) Infinity
(iii) Nil, since its not a part of sphere
(iv) Any
value depending upon its size
Q.10. A ray of light traveling parallel to the principal axis after reflection from a convex mirror,
(i) Always passes through its focus
(ii) Always passes through its centre
of curvature
(iii) Appears to come from its focus behind the mirror
(iv) Retraces its path
Q.12. A ray of light travelling in air falls obliquely on the surface of a calm pond. It will
(i) Go into the water without deviating from its path.
(ii) Deviate away from the
normal.
(iii) Deviate towards the normal.
(iv) Turn back on its original path.
Q.12. A thin lens and a spherical mirror have a focal length of + 15 cm each.
(i) Both are convex.
(ii) The lens is convex and the
mirror is concave.
(iii) The lens is concave and the mirror is convex.
(iv) Both are concave.
Q.13. A convex lens forms a virtual image when an object is placed at a distance of 18 cm from
it. The focal length will be
(i) Greater than 36 cm
(ii) Greater than 18 cm
(iii) Less than 36 cm
(iv) Less than 18 cm
Q14. An object is placed before a convex lens. The image formed.
(i) Is always real
(ii) May be real or virtual
(iii) Less than virtual
(iv) Is always erect
Q.15. An object is placed before a concave lens. The image formed
(i) Is always erect
(ii) May be erect or inverted
(iii) Is always inverted
(iv) Is always real
Q.6. A lens has a power of + 0.5 D. It is
(i) A concave lens of focal length 5 m
(ii) A convex lens of focal length 5 cm
(iii) A convex lens of focal length 2 m
(iv) A concave lens of focal length 2 m
Section – B
Q.1. Why a ray of light passing through the centre of curvature of a concave mirror retrace its
path after reflection?
Q.2. One wants to see an enlarged image of an object in a mirror. What kind of mirror should
one use and where should the object be placed?
Q.3. Which property of a concave mirror can be used to determine its focal length?
Q.4. What kind of mirror is used in vehicles to see the traffic following it?
Q.5. A man standing in front of a special mirror finds his image having a very small head, a fat
body and legs of normal size. What are the shapes of the three parts of the mirror?
Q.6. What type of mirror is formed when a mercury drop falls on the earth?
Q.7. Distinguish between real and virtual image.
Q.8. Draw ray diagrams to show the formation of images when the object is placed in front of a
concave mirror.
(i) Between its pole and focus point.
(ii) Between its centre of curvature and focus point.
Q.9. How will you distinguish between a plane mirror, a concave mirror and a convex mirror
without touching them?
Q.10. Define :
(i) Radius of curvature.
(ii) Principal focus
Q.11. Show that image distance is same as object distance when an extended object is placed in
front of the plane mirror.
Q.12. A short linear object of 2 cm. lies on the axis of a concave mirror of 15 cm. focal length at
a distance of 30 cm. from the mirror. What is the size of the image?
Q.13. The image behind a convex mirror (R = 68 cm) is located at 22 cm. from the mirror.
Where is the object located? What is the magnification produced? Write the nature of image
formed.
Q.14. Find the position, nature and size of the image of an object 4 cm high placed at a distance
10 cm from a concave mirror of focal length 20 cm.
Q15. Show that the mirror formula for spherical mirror also holds good for a plane mirror too.
Q.16. An object is placed at 10 cm from focus farther away from the mirror. If the image formed
is half the size of the object and real in nature, find the focal length of the mirror.
Q.17. An image double the size of the object is formed on placing an object in front of a mirror
of focal length 20 cm. Find the position (s) of the object.
Q.18. Which colour of the light reflected by an object will make it appear blue?
Q.19. What are the values of (i) the angle of incidence and (ii) the angle of reflection for the
normal incidence on a plane mirror surface?
Q.20. A concave mirror is placed in water. Will there be any change in focal length?
Q.21. A person wants to see the full image of tall building in a small mirror. Which type of
mirror should be used by him?
Q.22. What type of image is formed on a cinema screen?
Q.23. To use a concave mirror as a dentist‟s mirror, what should be the position of the teeth?
Q.24. If a plane mirror is rotated by an angle θ, by how will the angle between the incident and
the reflected ray change?
Q.25. A concave mirror is placed in water. Will there be any change in focal length?
Q.26. A person wants to see the full image of tall building in a small mirror. Which type of
mirror should be used by him?
Q.27. What type of image is formed on a cinema screen?
Q28. To use a concave mirror as a dentist‟s mirror, what should be the position of the teeth?
Q.29. Name the kind of mirror used to obtain. (i) a real and enlarged image (ii) virtual and
enlarged image.
Q.30. Name the kind of mirror used to obtain. (i) virtual and diminished image (ii) real and
diminished image.
Q.31. What happens to the speed of light when it undergoes reflection? Why?
Q.32. In the figure (a), AB is the object, A' B' is its image and MM' is the position of the mirror.
Complete the ray diagram and find the position of centre of curvature and focus of the mirror.
Also find the nature of the mirror
Q.33. Focal length of a convex lens is same as radius of curvature of a concave mirror. If the
mirror converges the light parallel to the principal axis at a distance of 10 cm from the pole
where does the same light beam converge by the lens?
Q.34. Show by ray diagram the formation of images by a convex lens in any two cases.
Q.35. A bird flies down vertically towards a water surface. To a fish inside the water, vertically
below the bird, how will the bird appears to be?
Q.44. A lens forms a real(i) Type of lens (ii) The image distance if f = 20 cm
(iii) The magnification
Q.45. Explain Myopia with the help of suitable ray diagrams. How can this defect of vision be
corrected? A boy uses spectacles of focal length – 50 cm. Name the defect of vision he is
suffering from. Compute the power of this lens.
Q.46. An object of size 3 cm is placed at a distance of 15 cm from a convex lens of focal length
10 cm. Calculate the distance and size of the image so formed. What will be the nature of the
image?
Q.47. Two cubes of equal size are placed on a newspaper. One cube is made of glass and the
other is made of a transparent plastic whose refractive index is higher than that of glass. When
viewed from above, below which cube will the letters appear nearer? Show the image
formation in any one case.
Q.48. Why is a convex lens called a converging lens and a concave lens, a diverging lens?
Q.49. How do you conclude that a ray of light incident towards the optical center of a thin lens
is transmitted almost without any deviation?
Q.50. The focal length of a convex lens is f. How does the size the image placed in front of it
change as the object is brought progressively closer to the focus from a distance which is just
greater than 2f?
Q.51. The refractive index of media A, B, C & D are 1.44, 1.47, 1.83, 1.33 respectively. In which
of these does the light travel (i) fastest (ii) slowest?
Q.52. When light undergoes refraction at the surface of separation of two media, what happens
to its wavelength?
Q.53. When does a ray of light neither refract nor deviate when passing through a glass slab?
Q.54. The power of a lens used in a reading glass of a person is +1D. What is the nature of the
lens?
Q.55. Light from a sodium-vapour street lamp is passed through a prism. What colours of light
do you expect to see if the transmitted light is allowed to fall on a piece of white paper?
Q.56. If one-half of a convex lens is painted black, will it form the complete image of an object.
Q.57. When a bird looks at a fish in water does it appear raised or deeper than it actually is?
When a fish looks at the bird does it appear nearer or further away?
Q.58. Copy the figure (a) and complete the formation of the image. What is the type of lens
used in the figure? What is the type of the image formed?
Q.59. Complete the following ray diagram in Figure (I-a) in which AB is the object an
A'B' is the image. Locate the lens and mark the focus of the lens by the letter F. What type of
lens is this? F1
Q.60. In Figure (I-b), state the position of object, position of image, nature of image when (i)
convex lens is used as burning glass (ii) convex lens is used in observing biological specimens.
Q.61. Which lens assist in reading a book? Which lens assist in reading from a blackboard in a
class?
Q.62. Can one burn a piece of paper by just using a convex lens instead of a matchstick or any
direct flame? Support your answer with the help of an appropriate ray diagram.
Q.63. What happens to the speed of light when it undergoes refraction? Explain why?
Q.64. In case of refraction of light through a rectangular glass slab, explain why (i) the emergent
ray is parallel to the direction of the incident ray (ii) the emergent ray is shifted sideward
slightly?
Human Eye And Colourful World
Q.1. The least distance of distinct vision for normal eye is
(i) Infinity
(ii) 25 m
(iii) 25 cm
(iv) 25
m
Q.2. The change in the focal length of eye lens is brought by.
(i) ciliary muscles
(ii) pupil
(iii) optical nerves
(iv) cornea
Q.3. Persistance of vision of eye is
(i) 1/10 sec.
(ii) 1/16 sec.
(iii) 1/100 sec.
(iv) cornea
Q.4. Electric pulses from retina to brain is conveyed via
(i) ciliary muscles
(ii) blind spot
(iii) pupil (iv) optical nerves
Q.5. Part of eye which is removed from eyes of dead body for eye donation is
(i) cornea
(ii) Retina
(iii) Iris
(iv) Pupi
Q.6. Accomodation of normal eye is from
(i) 5 cm to 15 cm
(ii) 1m to 3m
(iii) 15 cm to 1 m
(iv) 25
cm to infinity
Q.7. The splitting of white light into different colours on passing through a prism is called
(i) Refraction (ii) Reflection (iii) Dispersion (iv) Deviation
Q.8. Night vision device utilizes
(i) Infra – red rays
(ii) Ultra-violet rays
(iii) X - rays
(iv) γ – rays
Q.9. When white light falls on the glass prism, the least deviated colour is
(i) violet
(ii) orange
(iii) green
(iv) red
Q.10. Which one of the following colour has maximum frequency
(i) Red (ii) Violet
(iii) Green (iv) Yellow
Q.1. The far point of a shortsighted person is 1.5 m. Find the focal length, Power and nature of the
remedial lens.
Q.2. Complete the following figure.
Q.3. Why do different colours deviate differently in a glass prism?
Q.4. What is colour blindness?
Q.5. What are Rods and Cones? State briefly the functions of Rod & Cones.
Q.6. What is the iris ?
Q.7. Draw a labeled diagram of the human eye and give the basic details about its various parts.
Q.8. What is myopia? Draw ray diagrams showing the formation of image of an object at infinity and at
its far point by a myopic eye. Explain how this defect is corrected by using a concave lens.
Q.9. What is hypermetropia? Draw ray diagrams showing the formation of image by a hypermetropic
eye. For (i) a nearby object (ii) an object at the near point of the eye. How is this defect corrected by
using a convex lens?
Q.10. Why is the colour of the clear sky blue? reason behind twinkling of stars? Explain
H.O.T.S. Questions
Very Short Answer Type Questions [1 mark]
Q.11. How does the focal length of the eye lens change?
Q.12. Name the defect of vision due to
(i) Power of the eye is too great
(ii) Focal length of the eye lens is too great.
Q.13. Which color light is produced due to the scattering of sunlight by (i) very small-sized (ii) very largesized constituent particles of the atmosphere?
Q.14. Which property of the eye is used by cinematography to show motion pictures?
Q.15. Why the signal lights are red in colour?
Q.16. What happens to the image distance in the eye when we increase the distance of an object from
the eye?
Short Answer Type Question [2 marks]
Q.17. Why do clouds look white?
Q.18. Why is a normal eye not able to see clearly the objects closer than 25 cm?
Q.19. What is the relation between the wavelength of light and the size of the particles causing
scattering?
Q.20. When and where do we see a rainbow?
Q.21. A person is able to see objects clearly only when objects are lying at distances between 50 cm and
300 cm from his eye.
(i) What kind of defect of vision is he suffering from?
(ii) What kind of lenses will be required to increase his range of vision from 25 cm to infinity? Explain
briefly.
Short Answer Type Questions [3 marks]
Q.22. The alongside figure (a) shows a beam of white light falling on a glass prism gets split up into seven
colours marked 1 to 7, as shown in the diagram.
A student makes the following statement about the spectrum observed on the screen.
(i) The colours at position marked 3 and 5 are similar to the colour of the sky and the core of a hard
boiled egg respectively. Is the above statement made by the student correct or incorrect? Justify in
which two positions correspond closely to the colour of –
(a) A solution of potassium permagnate.
(b) „danger‟ or „stop‟ signal lights.
Q.23. A student finds the writing on the blackboard as blurred and unclear when sitting on the last desk
in the classroom. He, however sees it clearly when sitting on the front desk at an approximate distance
of 2 m from the blackboard. Draw ray diagrams to illustrate the formation of image of the blackboard
writing by his eye lens when he is seated at the (i) last desk (ii) front desk. Name the kind of lens that
would help him to see clearly even he is seated at the last desk. Draw a ray diagram to illustrate how this
lens help him to see clearly
NUMERICALS
1. A person with a myopic eye cannot see objects beyond 1.2m distinctly. What should be the nature of
corrective lens to restore proper vision? (P= -0.83 Lens – concave)
2. The near point of a hypermetropic eye is at 75 cm from the eye. What is the power of the lens
required to enable him to read clearly a book held at 25 cm from the eye? (P= 2.66
3. A myopic person uses specs of power – 0.5D. What is the distance of far point of his eye? (2m)
4. A person wants to read a book placed at 20 cm, whereas near point of his eye is 30 cm. calculate the
power of the lens required (1.67D)
5. The far point distance of a short sighted person is 1.5meters. find the focal length, power and nature
of the remedial lens? (-1.5 m, -0.67D, concave lens)
6. A person having a myopic eye uses a concave lens of focal length 10 cm. Find the power of the lens. (10D)
7. A person with myopic eye cannot see objects beyond 1.2metre distinctly. What should be the nature
of corrective lenses to restore proper vision?Ans: Here, distance of far point, x = 1.2mFor viewing distant
objects, focal length of corrective lens,F = -x = -1.2 mP = 1 / f = 1 / -1.2 = -0.83D
8. The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens
required to correct the problem? Ans: For diagram,Here, x’ = 1m = 100cm, d = 25cm, f =?From f = x’d /
x’- d, F = 100*25 / 100 - 25=33.3cmP = 100 / f = 100 / 33.3 = 3D
9. The far point of myopic person is 80 cm in front of the eye. What is the nature and power of the lens
required to enable him to see very distant objects distinctly? Ans: Concave; -1.25D
10. The far point of a myopic person is 150 cm in front the eye. Calculate the focal length and power of a
lens required to enable him to see distant objects clearly.Ans: -1.5m, -0.67D
Previous years questions
1.An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is
formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of
the lens.
[CBSE-All India 2007]
2. An object 20 cm tall is placed on the principal axis of a convex lens. Its 30 cm tall image is
formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of
the lens.
[CBSE-All India 2007]
3. Draw a ray diagram to show the
i. position and
ii. nature of the image formed when an object is placed between focus F and pole P of a
concave mirror.
[CBSE-DELHI 2006]
4. .An object is placed at a distance of 12 cm in front of a concave mirror. It forms a real image
four times larger than the object. Calculate the distance of the image from the mirror.
[CBSE-All India 2006]
5. A ray of light is incident on a convex mirror as shown below: complete the diagram
6. With respect to air the refractive index of water and benzene are 1.33 and 1.50 respectively.
Calculate the refractive index of benzene with respect to water.
[CBSE-DELHI 2005]
7. With respect to air the refractive index of kerosene is 1.44 and that for diamond is 2.42.
Calculate the refractive index of diamond with respect to kerosene.
[CBSE-DELHI 2005]
8. With respect to air the refractive index of ice is 1.31 and that of rock-salt is 1.54. Calculate
the refractive index of rock-salt with respect to ice.
[CBSE-DELHI 2005]
9. What are the values of (i) the angle of incidence, and (ii) the angle of reflection for normal
incidence on a plane mirror surface?
[CBSE-All India 2005]
10. Light enters from air into a glass plate which has a refractive index of 1.50. Calculate the
speed of light in glass. The speed of light in air is 3.0 x 108 ms-1.
[CBSE-All India 2005]
11. Light enters from air into water which has a refractive index of 1.33. Calculate the speed of
light in water. The speed of light in air is 3.0 x 108ms-1.
[CBSE-All India 2005]
12. Light enters from air into diamond which has a refractive index of 2.42. Calculate the speed
of light in diamond. The speed of light in air is 3.0 x 108 ms-1.
[CBSE-All India 2005]
13. A convex lens has focal length of 20 cm. Calculate at what distance from the lens should the
object be placed so that it forms an image at 40 cm on the other side of the lens?
State the nature of the image formed.
14. A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal
length 20 cm. The distance of the object from the lens is 30 cm. Find the (i) position, (ii) nature
and (iii) size of the image formed.
[CBSE-All India 2004]
15. An 8 cm tall object is placed perpendicular to the principal axis of a convex lens of focal
length 25 cm. The distance of the object from the lens is 30 cm Find the:
(a) position,
(b) nature and
(c) size of the image formed.
[CBSE-All India 2004]
16. If the magnification of a body of size 1 m is 2, what is the size of the imag
[CBSE-DELHI 2003]
17. Draw the following diagram in your answer-book and show the formation of image with
the help of suitable rays.
18. Draw ray diagrams to represent the nature, position and relative size of the image
formed by a convex lens for the object placed:
(a) at 2F1
(b) between F1 and the optical center O of lens.
[CBSE-All India 2008]
19. Copy this figure in your answer book and show the direction of the light ray after reflection:
20.If the convex lens produced four times magnified image [i]real image [ii] Virtual image. Given
focal length of the lens is 20cm.
21. Focal length of concave lens is convex lens is 20cm ,If it produced 1/3 times magnified real
image, Find the position of the image and object
22. In an experiment with a rectangular glass slab, a student observed that a ray of light
incident at an angle of 60o with the normal on one face of the slab, after refraction strikes the
opposite face of the slab before emerging out into air making an angle of 42 o with the normal.
Draw a labelled diagram to show the path of this ray. What value would you assign to the angle
of refraction and angle of emergence?
23.A person cannot see beyond 2 m .Write the defect of vision .How this defect can be
corrected ? Also find the power of lens
24. .A person cannot see below 50c m .Write the defect of vision .How this defect can be
corrected Also find the power of lens
25.If near point of a person shifted to 40cm. Write the defect of vision .How this defect can be
corrected Also find the power of lens