Science (Physic) SLC Important Question

Physics Important Question for SLC

Chapter 1
Force
Theoretical Questions
Q.1 .What do you mean by gravitational force?
Q.2 State Newton’s law of gravitation.
Q.3 Newton’s law of gravitation is called universal law. Why?
Q.4 State the factors that affect the gravitation.
Q.5 Mention any three applications of Newton’s law of gravitation.
Q.6 What is Newton’s gravitational constant?
Q.7 Write down the value and SI unit of gravitational constant.
Q.8 Mention any four consequences of gravitation.
Q.9 What is gravity? Write down its SI unit.
Q.10 What is acceleration due to gravity? Write down its SI unit.
Q.11 What is the value of acceleration due to gravity at the centre of the earth? Why do
tides rise in the sea?
Q.12 Define gravitational field intensity.
Q.13 Prove that: F= G m1m з/ d2
Q.14 Calculate the change in gravitational force between two bodies when the distance
between them is made double; keeping their mass constant.
Q.15 Mention what is the relation of force of gravitation with masses of the objects and
distance
Q.16 What is meant by the statement that the acceleration due to gravity on the surface of
the moon is 1.67 m/s2. ?
Q.17 List any two differences between universal gravitational constant (G) and
acceleration due to gravity (g).
Q.18 Write any two effects of gravity.
Q.19 Prove that: g œ1/ R2
Q.20 What do you mean by gravitational field?
Q.21 What is the relationship between the gravitational field intensity of a planet and its
radius?
Q.22 .what do you mean by the statement that the gravitational field intensity of the earth
is 9.8 N/kg?
Q.23 What is the direction of acceleration due to gravity? Give reason also.
Q.24 What is freefall? Rite down the conditions necessary for free fall.
Q.25 The earth’s orbit is oval in shape. Explain how the magnitude of the gravitational
force between the earth and the sun changes as the earth moves from position ‘A’ to ‘B’
as shown in the figure.
Q.26 Write down any two differences between mass and weight.
Q.27 What is the relation between the weight of an object and the radius of the earth?
Q.28 Weight of a body is found less at the top of mountain than that at its bottom. Why?
Q.29 What do you know about ‘feature and coin experiment’? Write down the conclusion
of feather and coin experiment.
Q.30 What do you mean by ‘weightlessness’? What are the conditions at which an object
having certain mass becomes weightless?
Q.31 What is difference between weightlessness in space and weightlessness on the
surface of the earth.
Q.32 If a body is dropped from the same height once in the equator and then in the polar
region, in which place will it fall faster? Explain with reason.
Q.33 When will an object inside the gravitational field of the earth be weightless?
Q.34 It is difficult to lift a larger stone on the surface of the earth but easy to lift smaller
one, why?
Q.35 Define mass. Writ down the characteristics and units of mass.
Q.36 Mention any two differences between gravity and gravitation.
Q.37 The weight of an object is more at polar region than that in the equatorial region of
the earth. Justify this statement.
Q.38 What happens to the force of gravitation between two objects when the mass of one
object is tripled, mass of other object is halved and the distance between them is tripled?
Q.39 What happens to the force of gravitation between two objects when the distance
between them is: (a) doubled? (b) Halved?
Q.40 Why does the weight of an object decrease with the increase in distance from the
centre of the earth?
Q.41 Write down the relationship of gravitational force with the distance between two
heavenly objects and their masses.
Q.42 If an iron ball and feather are dropped simultaneously in a vacuum, which one will
strike the ground first and why?
Q.43 What is the weight of a body at the centre of the earth? Why?
Q.44 What is relation between the gravitational field intensity and its radius? The weight
of a body is more at the polar region of the earth than at equatorial region, why?
Q.45 Observe the given diagram and answer the questions given below:
i.
ii.
Gravitational field intensity of the earth at B is з.5N/Kg. what does it mean?
Write the value of gravitational field intensity of earth at A and C.
Q.46
(a) An astronaut dropped a hammer and a feather on the moon. He was surprised that
both struck the surface of the moon at the same time. Why?
(b) Out of Figure ‘A’ an ‘B’ which one is filled with air? Explain with reason.
Q.47 An object thrown vertically upward from the earth’s surface returns back to the
surface of the earth, why?
Q.48 Define universal gravitational constant (G) and mention any two characteristics of
G.
Q.49 The weight of an object is less in a mine, why?
Q.50 What type of fall is called a free fall?
Q.51 Astronauts feel the weightlessness in space, why?
Q.52 What would have happened if there were no gravity in the earth? Give any three
effects.
Q.53 Why does value of gravitational field intensity of the earth vary from place to place
eon the surface of the earth?
Q.54 What effect in the value of ‘g’ is observed while going to the depth from the earth’s
surface? Explain with reason.
Q.55 Atmosphere is present on the surface of the earth but absent on the surface of the
moon, why?
Q.56 A man who can jump 1 meter high on the earth’s surface can jump 6 meter high on
the surface of the moon, why?
Q.57 The mass of the Jupiter is about 319 times greater than that of the earth, but its
gravitational field intensity is only about з.5 times greater than that of the earth. What is
the reason behind it?
Q.58 Two iron balls of masses 1 kg and 50 kg are dropped downward simultaneously fro
the same height, which one will reach on the surface of the earth faster? Explain with
reason.
Q.59 The acceleration due to gravity has no relation with mass of an object. Justify this
statement with one example.
Q.60 What are the factors that determine the weight of an object? What is the relation of
weight to these factors? Describe.
Q.61 Why do planets revolve around the sun? Write any two differences between freefall
and weightlessness.
Q.62 How was the theory propounded by Nicholas Copernicus proved by Galileo’s
investigation (discovery)? Describe in brief.
Q.63 Can the condition of weightlessness be called masslessness? In which condition
does F become equal to G?
Q.64 What is the acceleration of an object falling freely inside the gravitational field of
the earth? An object is weighed at Terai and at top of Mt. Everest. Where will the weight
of the object be greater? Give reason.
Q.65 The gravity of the earth is six times more than that of the moon, what does it mean?
Q.66 The value of ‘g’ at polar region of the earth is 9.83 m/s2. What does it mean? There
is very low effect of acceleration due to gravity in space very far away from the earth.
Justify this statement.
Q.67 Study the given figures and answer the following questions. Keeping the masses
constant, if the distance between two masses is doubled, how many times does the
gravitational force decrease?
Q.68 (a) What is the relationship between the radius of the earth and the weight of an
object? Mention any two differences between weightlessness due to freefall and
weightlessness in space.
(b) What is the magnitude of acceleration due to gravity in the space? Why? Give
reason regarding the fact that parachutists are not hurt when they jump out of
an airplane.
Q.69 An iron ball and feather are dropped simultaneously downward inside a vacuum
from the same height, which one will reach the ground first? Explain with reason.
Q.70 The probability of getting hurt is more when a man jumps from a significant height,
why?
Q.71 Write two differences between mass and weight of an object. If Kathmandu lies in
high altitude than Biratnagar from sea level, then where an object does has more weight
among two places? Give reasons.
Q.72 What is the change in the gravitational force between two bodies if the distance
between them is halved, keeping their masses constant? Define gravitational constant.
Numerical Problems
Q.1 If mass of the sun is 2 × 1030 kg, that of the earth is 6 × 10 24 kg and the distance
between them is 1.5 × 10 11 m. What is the gravitational force produced between them ?
(G = 6.67 × 10 -11 Nm2/kg2)
Q.2 Calculate the force of gravitational due to the earth on a boy weighing 20 kg standing
on the surface of the earth. [Mass of the earth is 6 × 10 24 kg and the radius is 6.4 × 10 3
km].
Q.3 Study the given diagram and calculate the mass of the object A. [G = 6.67 × 10
Nm2/kg2]
-11
Q.4 If mass of the sun is 2 × 1030 kg, that of the earth 6 × 10 24 kg and the distance
between them is 1.5 × 10 11 m. what is the gravitational force produced between them?
Q.5 The gravitational force produced between any two objects kept 2.5 × 10 4 km apart is
500 N. at what distance should they be kept so that the gravitational force becomes half?
Q.6 A man of 75 kg is standing on the surface of the earth having the mass of 6 × 10
kg, if the earth is 6380 km, calculate the force of attraction between man and earth.
24
Q.7 If the mass of the moon is 7.2 × 10 22 kg and radius is 1.7 × 10 6 m, what will be the
gravitational field intensity of the moon? What will be the weight of a man of 60 kg mass
on the moon?
Q.8 Calculate the acceleration produced on a unit mass placed at a distance of 3 × 10 5 km
from the moon, if the mass of the moon is 7 × 10 22 kg.
Q.9 Calculate the acceleration of the meteor when it is at the height of 10
centre of the earth. The mass of the earth is 6 ×10 24 kg.
7
m from the
Q.10 Study the given diagram and calculate the mass of the object A. the gravitational
force between A and B is 1.5 ×102 N.
Q.11 The mass of the moon is 7 × 10 22 kg and radius is 1740 km. calculate the
gravitational field intensity of the moon. Also, find out the weight of a person of mass 65
kg on the surface of the moon.
Q.12 The radius of the earth is 6.37 × 10 3 km and height of Mt. Everest from the sea
level is 8848 m, if the value of ‘g’ on the surface of the earth is 9.8 m/s2, calculate the
value of ‘g’ at the top of Mt. Everest.
Q.13 Calculate the force of gravitation acting between the objects ‘A’ and ‘B’ shown in
the given diagram.
Q.14 The gravity of the earth is six times greater than that of the moon. How much kg
mass can a person lift on the moon. How much kg mass can a person lift on the moon if
he can lift 80 kg mass on the earth?
Q.15 Calculate the acceleration of a meteor located at the height of 925 km from the
surface of the earth. The mass and radius of the earth id 6 × 10 24 kg and 6400 km
respectively.
Q.16 The mass of the earth is 6 × 1024 kg and the radius of the moon is 1.7 × 106 m.
calculate the gravitational field intensity of the earth is made to that of the moon by
compression.
Q.17 Study the given diagram and calculate the weight of an object of mass 15 kg placed
at the point ‘C’.
Q.18 What kg of mass can a weight-lifter on the Jupiter if he can lift 120 kg mass on the
earth. The gravitational field intensity of the Jupiter is 25 N/kg.
Q.19 Two objects of equal mass are kept 100 m apart. If the gravitation between them is 2
× 10 3, calculate the mass of each object.
Q.20 Two objects each of mass 1000 kg are kept 1 kilometer apart. Calculate the
gravitational force between them.
Q.21 The mass of the earth is 6 × 10 24 kg. Study the given diagram and calculate the
gravitational field intensity of the earth the point ‘A’. What is the weight of an object
having mass 45 kg placed at the point ‘A’?
Q.22 The mass of the Jupiter is 1.9 × 10 27 and that of the sun id 2 × 10 30 kg. If the
gravitational force between them is 4.166 × 10 23 N. Calculate the distance between the
sun and Jupiter.
Q.23 Calculate the mass of an object of weight 85 N placed at the height of 1.8 * 10 4 km
from the surface of the earth.
Q.24 Calculate the weight of the object of mass 45 kg on the surface of the earth and
moon. The value of acceleration due to gravity on the earth’s surface is 9.8 m/s2 and on
the moon is six times less than that on the earth,
Q.25 Study the given diagram and calculate the mass of the object ‘A’. The gravitational
force between those objects is 1.5 × 10 2 N.
Q.26 Calculate the mass of the planet if the weight of an object of mass 50 kg at the point
‘B’ is 54N.
Q.27 The mass of the earth is 6 × 10 24 kg and its radius is 6400 km. calculate the weight
of an object of mass 250 kg on the surface of the earth.
Q.28 Two metal balls of equal mass are kept at a distance of 100 meter from their centers.
If the gravitational force between them is 1575 N, calculate the mass of each sphere.
Q.29 Study the given figure and find out the gravitational field intensity of the given
planet?
Q.30 The radius of the earth is 6.37 × 10 3 km and the height of Mt. Everest is 8848 m
from the sea level. If the value of acceleration due to gravity (g) is 9.8 m/s2 at the surface
of the earth, calculate the value of acceleration sue to gravity at the top of Mt. Everest.
Q.31 The mass of the earth is 6 × 10 24 kg and its radius is 6400 km what is the mass of a
man weighing 977 Newton in a spring balance? (Universal gravitational constant is 6.67
× 10 Nm2/kg2 and uses all the data given in the question.)
Chapter 2
Pressure
Theoretical questions
Q.1 Define pressure. Write down its formula and SI units.
Q.2 What is thrust? Write down its SI units.
Q.3 Name the factors on which pressure depends. Also, show their relation with the
pressure being exerted.
Q.4 Prove that: P = F / A, where symbols have their usual meanings.
Q.5 Define one Pascal pressure.
Q.6 On what factors does the pressure of liquid depend on?
Q.7 State Pascal’s law. Name equipment which works on the basis of Pascal’s law and
write its one use.
Q.8 Prove that: P = hdg.
Q.9 What is hydrometer? Why does a hydrometer have a heavy bulb and a narrow stem?
On which principle does it work?
Q.10 Write down any two factors on which the upthrust depends?
Q.11 Prove that upthrust = Vdg (where V = volume of the object, d = density of the liquid
and g = acceleration due to gravity.)
Q.12 Liquid transmits the pressure equally in all direction. Which law does this statement
represent? Speed of flow of water from tap of upper floor is less than that from the tap of
down floor, why?
Q.13 What do you mean by upthrust? Write down its unit in SI system.
Q.14 State the law of floatation. Describe the structure of hydrometer in brief.
Q.15 In which law is the given experiment based? State this law. Prove that P=hdg.
Q.16 Name the instrument given in the diagram. What weight of water is displaced by the
instrument? Give reason also. Name the law on which it is based. Give a use of this
instrument.
Q.17 Two objects having same volume are shown in the figure. Which one experiences
more upthrust? Describe with reason.
Q.18 What is lactometer? The weight of a stone in three different media – air, water and
solution of common salt are given. Study the given table and answer the following
questions.
Medium Weight
A
24N
B
28N
C
19N
Which one is water and which one is air out of three media? Why?
Q.19 What is the effect of density of liquid on the flotation of an object? In which law is
the experiment based? State this law.
Q.20 When does a body float in water? Why does an egg sink in fresh water but float in
salty water?
Q.21 As in the given figure, if two hydrometer are partially immersed in fresh water and
salt water, which one is salt water in between ‘A’ and ‘B’. On which law does the
working of hydrometer base? An iron nail sinks in water but a huge ship made of iron
floats on water, why?
Q.22 One of the two ladies with same weight is wearing pointed heeled shoes and other
wearing flat shoes. Explain which one exerts more pressure on the ground.
Q.23 Two rectangular water tanks, one (A) having a larger base area than the other (B),
carry equal volume of water. Explain whose bottom experience more pressure?
Q.24 What is the change in pressure at the bottom of a drum filled with water if it is
brought to Himalaya from Terai? Write with reason.
Q.25 What is the resultant pressure exerted upon the surfaces AD and BC and why? Out
of surfaces AB and DC which surface experiences more pressure and why?
Q.26 The figure shows a hydrometer floating in fresh water, з cm of stem of the
hydrometer is outside the surface of the water. Study the diagram and answer the
following questions. What is function of hydrometer? What will happen id the fresh
water is replaced by salty water?
Q.27 Although a ship is made up of iron, it can float on water, why?
Q.28 When a piece of ice floating on water in a bucket melts, the level of the water does
not rise, why?
Q.29 During dipping out of water from a well, it is easier to lift the bucket while it is still
inside water than when it is out of water. Why?
Q.30 What is a hydraulic press? How is the applied force multiplied by hydraulic press?
Give its two applications.
Q.31 What is hydrometer? Explain its function with diagram.
Q.32 How much water should be displaced by a body having weight 750N to float in
water? Which one is the salt solution of the diagram A and B? Why?
Q.33 Give reasons
i.
Studs are made on the sole of the football player’s boot.
ii.
It is difficult to walk on bare feet in a graveled road.
iii. The rear wheels of a tractor are made larger and flat.
iv.
The tyres of heavy vehicles are made double-wheeled.
v.
The blood pressure in human feet is greater in feet than in head.
Q.34 Deep sea divers wear special diving suits. Explain the reason.
Q.35 Sharp knife cuts vegetable more easily than a blunt one. Give reason.
Q.36 The water supply tanks are placed higher than any other building in a town. Explain
the reason.
Q.37 Walls of a dam are made thicker at the bottom. Explain the reason.
Q.38 Describe an experiment with a neat diagram to prove the Pascal’s law of liquid
pressure.
Q.39 Name the equipments which are based on the principle of Pascal’s law of liquid
pressure
Q.40 What is the principle of hydraulic machine? Prove that: F2/F1 = A2/A1
Q.41 Why are hydraulic brakes used? Explain the construction and working of hydraulic
brake with a labeled diagram.
Q.42 Draw a neat and labeled diagram showing hydraulic press. Mention the uses of
hydraulic press.
Q.43 Write down the use of hydraulic jack. (Lift)
Q.44 State the factors affecting upthrust.
Q.45 Prove mathematically that upthrust is equal to the weight of the liquid displaced.
Q.46 Prove that: Upthrust = Adg (h2 – h1)
Q.47 Prove that: Upthrust = Vdg
Q.48 What is the cause of upthrust? Describe in brief.
Q.49 What is the relation between upthrust, actual weight and apparent weight (Loss in
weight) of an object?
Q.50 Study the given diagram and answer the following questions:
i.
ii.
What is the upthrust given by the liquid?
On which principle is this experiment based?
Q.51 What is density? Write down its formula and SI unit.
Q.52 What do you mean by relative density? Write down various formulae which are
used to calculate relative density. What is the unit of relative density? Why?
Q.53 What is hydrometer? State the principle used in its working.
Q.54 Describe the structure of a hydrometer with a labeled diagram.
Q.55 Give reasons:
i.
The gravity bulb of hydrometer is made heavier.
ii.
The flotation bulb of hydrometer (buoyancy bulb) is made small.
iii. The stem of hydrometer is marked from top to bottom not uniformly graduated.
Q.56 What is lactometer? Draw a neat diagram showing a lactometer.
Q.57 Differentiate between Archimedes’ principle and law of floatation.
Q.58 What is the relation between density of a body and floatation?
Q.59 State the conditions that determine the sinking or floatation of a solid when the solid
is placed in a liquid.
Q.60 Give reasons:
i.
ii.
iii.
iv.
v.
vi.
vii.
An egg sinks in fresh water but floats in a strong solution of salt.
Iceberg floats in water.
An iron nail sinks in water but ship made up of iron floats.
It is easier for a man to swim in sea water than in river water.
A dead body floats with its head immersing in water.
An iron nail sinks in water but floats in mercury.
It is easier to lift a heavy stone inside the water.
Q.61 Study the given table and answer the following questions:
Substances (Liquid) Density (gm/cm3)
A
11
B
13.6
C
1
D
0.9
i.
Among the substances A, B, C and D; which substance floats on water, why?
ii.
Among the given substances, name the substance that gives greatest upthrust.
Give reason also.
Q.62 Which law can be explained by the given figures?
Q.63 Ballast tank in submarines are filled with water diving. Explain the reason.
Q.64 Why are passengers not allowed to stand on boat?
Q.65 Heavy loads of trucks can be stopped by applying a small force. How is it possible?
Explain.
Q.66 State Pascal’s law.
Q.67 If a small stone is weighed first in air (A) and then in water (B), as a given in the
diagram, in which condition (A or B) will have greater weight and why? Which law can
be verified from the given experiment? What differences will be observed if Eureka can
is filled with salt water instead of fresh water? Give reason.
Q.68 State, what law can be explained by the use of the appliance given in the diagram.
NUMERICAL PROBLEM
Q.1 The volume of a block is 24000 cm3 and its density is 0.9 gm/cm3. How much part of
it remains above the surface of water when it is kept in water?
Q.2 A rectangular body is completely dipped in water as shown in the given figure. It’s
upper or lower surface area of it is 2m2. Find the upthrust acted upon it due to water.
(Density of water is 1000 kg/m3)
Q.3 A 4 cm long glass rod weighing 10 g weighs 7 g in water of density 1 g/cm3.
Calculate the density of glass and area of cross-section of the glass rod.
Q.4 An object with dimensions 24 cm × 18 cm × 12 cm is dropped into a vessel
containing water. If 3 cm height of the object and weight of water displaced.
Q.5 If a man has mass60 kg and the area of his one foot is 150 cm2, what is pressure
exerted by him on the ground when he stepped with one foot.
Q.6 The density of sea water is 1030 kg/m3 and that of the iceberg is 920 kg/m3. What
percentage by volume of the iceberg is lying outside the water?
Q.7 Figure shows a hydrometer floating in a certain liquid. The hydrometer reads the
density of the liquid 800 kg/m3 and the volume of the submerged part of the hydrometer
is 5 × 10 -5 m3. Calculate the weight of the hydrometer.
Q.8 Calculate the mass of displaced water when 30 cm thick iceberg with surface area
1000 cm2 floats on water. (Density of ice = 0.9 g/cm3, density of water = 1 b/cm3)
Q.9 If the cross sectional area of narrow cylinder is 40 cm2 and that of the wide cylinder
is 4 m2, what load is necessary on the piston B to balance 600 N load kept on piston A?
Q.10 The weight of piece of stone when completely immersed in water is 12N and it
displaces 8N of water. What is weight of the stone in air?
Q.11 If the density of an object is 2.5 g/cm3 and its mass is 1 kg, then what amount of
water will be displaced when the object is placed in water? Density of water = 1 g/cc, g =
10 ms-1.
Q.12 Height of mercury column of a barometer is 50*10-2 m. If the density of mercury is
1.36 * 10 4 kgm-3, what is the pressure of the mercury column? (g = 10 ms-2)
Q.13 The depth of water in a rectangular tank is 6 m, find the water pressure exerted at
the bottom of it. (g = 10 ms-2)
Q.14 A rectangular body is dipped into water as shown in the figure. The upper or lower
surface area of it is з sq. meters; find out the upthrust acted on in due to water. (The
density of water is 1000 kg/m3).
Q.15 What will be the pressure exerted per square meter on its bottom, when a water tank
of 1 m each of length, width and height is completely filled with water?
Q.16 Study the given diagram and answer the following questions:
(a) What is the pressure at A?
(b) What is the pressure at B?
(c) Calculate the thrust (F2) on piston B.
Q.17 An object having surface area of 40 cm2 is immersed in water of density 1000
kg/m3. Study the given figure and calculate the upthrust. What is the weight of the water
displaced by the object? Why?
Q.18 What part of block of wood remains immersed in water of density 1000 kg/m3 when
the block of wood placed in water having density 800 kg/m3? (The dimension of wooden
block is 4 cm × 8 cm × 5 cm).
Q.19 The weight of a piece of stone when immersed in water is 9N and it displaces 2N of
water. What is the weight of the stone in air? On which principle is the experiment
based?
Q.20 In a hydraulic press, the cross section area of small piston is 8 cm2 and that of the
large piston is 0.4 m2. What force must be applied on the small piston in order to lift a
weight of 12 kg?
Q.21 Calculate the mass of water displaced when a piece of ice having 50 cm length, 30
cm breadth and 20 cm height kept on water. The densities of ice and water are 0.92
gm/cm3 and 1 gm/cm3 respectively.
Q.22 In a hydraulic machine, the cross-sectional area of smaller piston is 30 cm2 and that
of larger piston is 900 cm2. if a smaller piston, calculate:
(a) The pressure on the smaller piston.
(b) The pressure on the larger piston.
(c) The maximum load that cab be lifted on larger piston.
Q.23 An object weighs 20 N in air and 15 N in a liquid.
(a) What is the upthrust of the liquid on the object?
(b) What is the weight of the liquid displaced?
Q.24 Calculate the amount of force required on a small piston of cross-sectional area з
cm2 to balance a weight of 1500N kept on a piston of area 20 cm2.
Q.25 An object of weight 40 N in air weighs 20 N when immersed in water and 30 N
when immersed in a liquid of unknown density. Find out the density of the unknown
liquid? Density of water is 1000 kg/m3.
Q.26 Study the given figure and calculate the pressure at the points A and B.
[Density of Hg = 13.6 g/cm3 and g= 9.8 m/s2]
Q.27 Study the second figure above and calculate the amount of force to be applied on the
small piston to support 1000 N weight in the large piston.
Q.28 In a hydraulic press, the surface area of small piston is 0.02 m2 and that of bigger
piston is 2 m2. if a force of 100N is applied on small piston, then
i.
What is the pressure acting on the liquid?
ii.
What is the force acting on piston B?
iii.
Calculate the pressure acting on piston ‘B’.
Q.29 If a boat with mass 200kg displaces 3m3 of water, when it floats safely. What is the
maximum mass that can be carried by it safely? Density of water 1000 kg/m3.
Q.30 The cross-sectional area of piston A is 0.1 m2 and that of piston B, C and D is 0.2 m2
each. Calculate the pressure exerted at piston B, C and D by applying a force of 200 N on
piston A.
Q.31 If pistons A, B and C of the apparatus given in the diagram are supposed to be
friction less, what is the area of the piston B? What force is exerted on the piston C?
Q.32 If area of the piston A is 0.05 m2 and that of B is 0.15 m2, what force is to be
produced in B when 20 N forces is applied in piston A.
Q.33 Id the length, breadth and thickness of wooden block with density 0.8 g/cm3 are 20
cm, 15 cm and 10 cm respectively and it is partially immersed in water with density 1
g/cm3, answer the following questions:
(i)
Find the volume of wood.
(ii)
Calculate the mass of the block.
(iii) How much water is displaced?
(iv)
Find the thickness of the block above the surface of water.
CHAPTER 3
Energy
Theoretical Questions
Q.1 What do you mean by source of energy? Give four examples.
Q.2 Define renewable source of energy with two examples.
Q.3 What are non-renewable sources of energy? Give two examples.
Q.4 Mention any two differences between renewable and non renewable sources of
energy.
Q.5 The Sun is the main source of energy. Give two reasons to justify this statement.
Q.6 Explain why we might face energy crisis in a near future.
Q.7 What is energy crisis? How can it be overcome? Give any two ways.
Q.8 What is fossil fuel? Give an example. Write two reasons why higher priority is given
for the production of hydroelectricity in Nepal.
Q.9 What is geothermal energy? The development of hydropower helps to reduce energy
crisis further, justify. Write two advantages of the hydropower.
Q.10 “Fossil fuel is also an outcome of solar fuel energy.” Justify this statement with
reasons.
Q.11 Suggest any two alternative ways to prevent the energy crisis in the context of
Nepal.
Q.12 What is nuclear fuel? Give two reasons to justify that the use of hydroelectricity
should be increased more than that of fossil fuel energy.
Q.13 “Energy crisis is the problem crated by human itself”. Justify the given statement
with your suitable argument.
Q.14 Suggest any two alternative ways to meet the demand of energy in our country.
Q.15 “Fossil fuel is also an outcome of solar fuel energy.” Justify this statement with
reasons.
Q.16 Briefly describe how energy is produced in the sun. List any four alternative sources
of energy that are relevant to Nepal.
Q.17 How is nuclear energy produced? Nepal has high potentiality for producing
hydroelectricity however difficult to produce it. Give one reason of each.
Q.18 What is the cause that coal and petrol are called non-renewable sources of energy?
Q.19 Nowadays, it is found that government has encouraged using the bio-gas, why?
Q.20 Write down two causes of extreme use of petrol although it is a non renewable atom
in the sun.
Q.21 Give the equation of process showing the formation of helium atom from hydrogen
atoms in the sun.
Q.22 What is hydro-energy? Give its three important applications in our country.
Q.23 . Why do you think the world should shift its energy dependence from non-
renewable sources to renewable sources?
Q.24 Nuclear energy is considered as boon as well as curse to our present day world.
Justify the statement.
Q.25 Why is the demand of nuclear energy saving? Give any three methods of energy
saving.
Q.26 Mention any two applications of geothermal energy.
Q.27 Why is the demand of nuclear energy increasing?
Q.28 Write down any two ways of preventing energy crisis.
Q.29 Name any two main sources of energy used in world. Write two measures to
conserve them.
Q.30 The use of alternative source of energy helps to control the energy crisis, how?
Q.31 The government of Nepal has been hiking the price of petroleum produce from time
to time. Suggest two ways how hiking the price of petroleum products helps in pushing
the problem of energy crisis further into the future.
Q.32 Why is possibility of energy crisis in the world?
Q.33 What is thermonuclear fusion reaction? Write down a cause of energy crisis.
Q.34 What is energy crisis? Write down a way to control energy crisis.
Q.35 What is the ‘alternative energy sources necessary to increase in today’s world?
Q.36 What can be the best alternative source of energy in Nepal and why?
Q.37 Write down two causes of extreme uses of petrol, although it is a non-renewable
source of energy.
Q.38 Why the sun is called main source of energy? What is energy crisis? Write the
measures to reduce it.
Q.39 What is nuclear fusion? Describe the nuclear fusion taking place I the sun with
chemical equation.
Q.40 “Nepal has high potentiality of producing hydro-electricity”. Prove this statement
with two reasons.
Q.41 Write any four necessary conditions required to take place nuclear fusion reaction in
the sun.
Q.42 Why is government of Nepal assisting the farmers, who make gobar gas plants
providing technical man power ad financial support? What role does gobar gas play to
solve energy crisis?
Q.43 Show the difference between nuclear fusion and nuclear fission with an example of
each. What is deuterium?
Q.44 Explain briefly why there is an acute need of the search for alternative sources of
energy on earth.
Q.45 How is the enormous amount of energy produced in the Sun? Describe it with
balanced chemical equation.
Q.46 Give a measure to push further the energy crisis.
Q.47 What type of energy sources are referred as alternative energy sources?
Q.48 Justify giving three reasons that the use of hydropower should be increased than that
of coal and mineral oil for energy
Q.49 What is the cause that coal and petrol are called non-renewable source of energy?
Nowadays, it is found that government has encouraged using the bio-gas. Why?
Q.50 Scientists are seen very busy to design the solar power depending equipments.
Why?
Q.51 Write two ways to be protected fro the state of energy crisis.
Q.52 Give one main factor that causes energy crises. How does a nuclear reaction occur?
Explain with a chemical reaction.
Q.53 List four renewable sources of energy.
Q.54 “Development of renewable source of energy is the right solution of energy crisis.”
Justify this statement.
Q.55 What is the use of formula E= mc2? What do symbols E, m and c stand for? Who
propounded this equation?
Q.56 Write down two causes of extreme use of coal and petroleum.
Q.57 Define wind energy. Solar energy and biomass energy can solve the problems of
energy crisis in Nepal, how? Explain it in brief.
Q.58 Which is the most useful energy source for a country like Nepal? Give any two
reasons in support of your answer. The world will have to face energy crisis in near
future. Why?
Q.59 Solar energy is more important than the fossil fuels, why?
Q.60 What is deuterium? What is the process of its formation? State the conditions
needed for this process.
Q.61 Explain the statement that hydroelectricity id the product of solar energy. State any
three uses of hydroelectricity.
Q.62 Bio-gas is considered as very useful for farmers. Why? Give any two reasons of
hydropower being very popular. Prove this statement with three reasons.
Q.63 What is thermonuclear fusion reaction? Write any two points to justify that
urbanization brings energy crisis.
Q.64 What is hydroelectricity? “Nepal has high
hydroelectricity”. Prove this statement with three reasons.
potentiality
of
producing
Q.65 Give two reasons why hydroelectricity could be better alternative of bio-fuel in the
context of our country. Suggest two ways of conservation of energy in order to avoid
energy crisis.
Chapter 4
Heat
Q.1 Define heat. Write down its SI unit.
Q.2 What do you mean by 1 calorie of heat energy?
Q.3 What do you mean by 1 joule of heat energy?
Q.4 What is meant by the statement that the specific heat capacity of mercury is 128 J/Kg
C? Two objects A and B have equal masses. But the object A has more specific heat
capacity than B. now, if both of them are given with equal amount of heat, whose
temperature will be more and why?
Q.5 Give two differences between heat and temperature. Aquatic animals are found alive
in the pond with frozen surface, why?
Q.6 Write SI unit of heat and temperature. Change 1 calorie into Joule.
Q.7 What is anomalous behavior of water? Can water be used as the heating agent, to
prevent the other liquid from freezing, in the cold countries? Why?
Q.8 What is the temperature of water at the bottom of the pond given in diagram? Give
reason to your answer. Why does ice float on waster? Where do the aquatic animals stay
in it?
Q.9 Define temperature and state its SI unit. A glass is filed with certain liquid at certain
temperature such that it overflows whether heated or cooled. Suggest, with justification,
the name of the liquid in the glass and its temperature.
Q.10 Water is used to cool down the motor engine, why?
Q.11 What is anomalous property of water? Write its one importance for aquatic
organism.
Q.12 Define heat and temperature in terms of molecular kinetic theory.
Q.13 What do you mean by the specific heat capacity of water is 4200 J/Kg C? Write
down the reason regarding the fact that there is very cold during night and very hot
during the day in desert.
Q.14 What do you mean by heat capacity and specific heat capacity?
Q.15 What is the relationship between the molecular vibration of an object and its
temperature?
Q.16 Specific heat capacities of three different metals are given in the table below.
Answer the following questions on the basis of the table.
Metal
Specific
heat
capacity
A
380 J/kg ̊C
B
470 J/kg ̊C
C
910 J/kg ̊C
What is the cause that ‘C’ metal have the lowest temperature among the three metals of
same temperature and masses when all of them are given same heat? Which metal ball
will penetrate into the greatest depth if each with equal mass is put on a wax-slab after
heating to 200 C and why?
Q.17 What changes in volume will be observed when water is heated from 0 C to 10 C?
At what temperature water has the highest density? Who is benefited from that property
of water and how?
Q.18 Water in an earthen pot remains cold in summer, why?
Q.19 What does it mean by the statement that specific heat capacity of a substance is 510
J/kg ̊C?
Q.20 What is calorimetry? State the principle of calorimetry.
Q.21 The climate around the sea remains constant. Why?
Q.22 State any two practical advantages of high specific heat capacity of water.
Q.23 In winter, steel chairs are felt colder than wooden chairs. Why?
Q.24 Which one of the following contains higher amount of heat and which one has
higher temperature? Explain with reason.
i.
A bucket full of hot water
ii.
A burning matchstick
Q.25 What is temperature? State the meaning of specific heat capacity of copper is 380
J/kg ̊C.
Q.26 What is the cause of using water to cool down the motor engine? What is the
maximum possible temperature of water at the bottom of a pond when its surface water
freezes?
Q.27 A breaker is filled with water. Not a single drop can be added. The temperature of
water is 4 ̊C. What will happen if it is cooled? Explain with reason.
Q.28 Specific heat capacities of paraffin oil and water are 2200 J/kg ̊C and 4200 J/kg ̊C
respectively. If equal amount of heat is given separately to equal mass of both, which one
will have greater temperature after 20s and why?
Q.29 If the water at 4 ̊C is cooled, what will be the effect on it density?
Q.30 Water is used to cool the engine of vehicle, why?
Q.31 State formula of heat equation. Why the fishes do not die even when the pond water
is frozen?
Q.32 Why is the density of water highest at 4 ̊C? The specific heat capacities of four
different metals A, B, C and D are shown in the given chart. If 4 balls of different metals
with equal mass are heated to 200 ̊C and put on the wax slab, the ball made of which
metal will penetrate deepest and why?
Metals
A
B
C
D
Specific heat capacity
900 J/kg ̊C
380 J/kg ̊C
500 J/kg ̊C
239 J/kg ̊C
Q.33 In the figure given below, iron ball and copper ball A and B respectively having
temperature 200 ̊C and equal masses, are kept on wax blocks. Which one makes a deeper
hole and why? (sp. heat capacity of iron is 470 J/kg ̊C and that of copper is 380 J/kg ̊C)
Q.34 At what temperature water has highest density? Which is benefited from this
property of water? And how?
Q.35 At what temperature is the density of water highest? If the water with that
temperature is cooled. What is its effect on density?
Q.36 What is the relation between the specific heat capacity and the rate of increase or
decrease in its temperature?
Q.37 Specific heat capacities of three different metals are given I the table below. Answer
the following questions on the base of the table:
Metals
A
B
C
i.
ii.
iii.
Specific heat capacity
910 J/kg ̊C
380 J/kg ̊C
470 J/kg ̊C
The specific heat capacity of metal C is 470 J/kg ̊C. what does it mean?
Which metal will have lowest temperature if all the three metals with same mass
and temperature are given equal amount of heat? Why?
Which metal ball will penetrate to the greatest depth if each with equal mass is
put on a wax-slab after heating to 100 ̊C? Why?
Q.38 Define the term ‘Heat’. If heat is supplied to a solid continuously, it melts. Give
reason to this.
Q.39 Answer the following question studying the table:
Substance
Specific Heat Capacity
X
138 J/kg ̊C
Y
470 J/kg ̊C
Z
2100 J/kg ̊C
If equal heat is given to equal masses of the three substances, which one will have the
lowest temperature?
Q.40 Explain why:
i.
A bottle completely filled with water gets burst when it is kept in a refrigerator.
ii.
A cloudy night becomes warmer than a clear night.
Q.41 What is the relation between the vibration of molecules of a substance and its
temperature?
Q.42 Write down the cause that the night of desert is very cold and day of that is very hot.
Q.43 What is the temperature of water at the bottom of a pond in cold and day of that is
very hot.
Q.44 Iron is heated faster than water, why?
Q.45 What is the relation between joule and calorie?
Q.46 We wear warm clothes in winter, why?
Q.47 Name an instrument that is used for measuring amount of heat.
Q.48 If 1 kg of water and 1 kg of mercury is heated together then which one will have
higher temperature? Why?
Q.49 Explain how does this specific heat capacity of water help to keep the temperature
of the land nearby the ocean moderate?
Q.50 What effect will be seen on the volume of water when it is heated from 0 ̊C to 10 ̊C?
What is this type of behavior of water called? How is this behavior of water useful for
aquatic life?
Q.51 Prove Q = mst. (Where Q = amount of the heat gained or lost, m = mass of the body,
s = specific heat and t = change in temperature.)
Q.52 What are the factors on which the heat gained or lost by a body depends? Also show
their relations.
Q.53 What will happen if oil used in a hot water bag, why? Milk boils faster than water,
why?
Q.54 Water freezes from the top while ghee freezes from bottom, why?
Q.55 What is the relation between the specific heat capacity and rate of increase or
decrease in the temperature? Water kept in an earthen pot during summer is colder than
that in a metal pot. Why?
Q.56 If three liquids ‘A’, ‘B’ and ‘C’ having equal masses are kept in same type of
container and placed in sun for 10 minutes. The change obtained in temperature is given
in the table.
i.
ii.
Liquid Increase in temperature
A
10 ̊C
B
20 ̊C
C
5 ̊C
Which liquid has the highest specific heat capacity? Why?
If equal mass of all three liquids at same temperature are cooled then which one
will cools down faster? Why?
Q.57 Give reasons.
i.
Well water is warmer in the morning during winter.
ii.
It is very hot during day and very cold during night in a desert.
Q.58 The graph shows the relation between densities of water with its temperature. Study
the graph and answer the following questions:
i.
ii.
What happens in the density of water if it is cooled below 4 ̊C and heated above
4 ̊ C why?
At what temperature water has highest density and lowest volume.
Q.59 A beaker filled with water at 4 ̊C overflows whether it is heated or cooled why?
Q.60 Write down the boiling point of and freezing point mercury. Why is mercury used as
a thermometric liquid?
Q.61 Define heat and write its SI unit.
Q.62 Clarify with example the relationship between heat and temperature.
NUMERICAL PROBLEMS
Q.1 The specific heat capacity of mercury is 138 J/kg ̊C. How much heat is required to
increase the temperature of 2 kg of mercury by 50 ̊C?
Q.2 The temperature of 2 kg of water is 10 ̊C and 84000 J of heat is applied in it, what
will be its temperature (final temperature) after it?
Q.3 What is the final temperature of mixture of 10 kg of water at 70 ̊C and 20 kg of water
at 10 ̊C? (Neglect the heat absorbed by the container).
Q.4 What quantity of heat energy is needed if 20 liters of water is to be heated from 20 ̊C
to 35 ̊C? (Sp. Heat of water = 4200 J/kg ̊C)
Q.5 If 15 kilojoules heat energy is required to raise the temperature of a substance of
mass 2 kg through 20 ̊C, calculate the specific heat capacity of that substance.
Q.6 When 9.4 kJ of heat energy is supplied to 2 kg mass of an iron ball the temperature of
the ball increases by 10 ̊C. calculate the specific heat capacity of iron.
Q.7 If a metal ball having of mass 2000 gram and temperature 300 ̊C is dropped in 5 kg
water at 20 ̊C, the final temperature of water reaches 35 ̊C. Calculate the specific heat
capacity of the metal ball.
Q.8 Calculate the amount of heat required to raise the temperature of 20 kg water from
10 ̊C to 90 ̊C? (Sp. Heat capacity of water is 4200 J/kg ̊C)
Q.9 What amount of heat energy is required to raise the temperature of 5 kg copper from
10 ̊C to 90 ̊C? The specific heat capacity of copper is 400 J/kg ̊C.
Q.10 How much heat is required to raise the temperature of 100 gm of water from 10 ̊C to
90 ̊C? (Sp. Heat capacity of water is 4200 J/kg ̊C)
Q.11 10 kg water at 5 ̊C is mixed with 5 kg water at 90 ̊C. calculate the temperature of
mixture.
Q.12 Hoe much heat is required to raise the temperature of 150 gm of iron ball from 25 ̊C
to 150 ̊C? (Sp. Heat capacity of iron = 480 J/kg ̊C )
Q.13 Calculate the amount of heat required to raise the temperature of 5 kg alcohol from
20 ̊C to 50 ̊C. the specific heat capacity of alcohol is 2400 J/kg ̊C.
Q.14 Calculate the amount of heat energy required if a Shreya wants to increase the
temperature of 20 kg of water from 16 ̊C to 40 ̊C to have a warm bath.
Q.15 Sona needs 20 kg of water at 36 ̊C to take a bath, but her water is only at 16 ̊C.
calculate the minimum amount of heat energy she required to heat the water to the
required temperature.
Q.16 If 433.2 kilo joule of heat is necessary to heat 2 kg of copper ball from 30 ̊C to 600
C, what is the specific heat capacity of copper?
Q.17 What quantity of heat energy is required to if 50 liters of water is to be heated to
37 ̊C for bathing purpose? The specific heat capacity of water is 4200 J/kg ̊C and liter of
water has 1 kg mass.
Q.18 Calculate the amount of heat required to raise the temperature of 50 kg of water
from 10 ̊C to 60 ̊C. (Specific heat capacity of water is 4200 J/kg ̊C).
Q.19 What will be the specific heat capacity of water if 2.1 × 10 5 joules of heat energy is
required to raise the temperature of kg of water from 15 C to 40 C?
Q.20 Calculate the amount of heat required to raise the temperature of a frying pan by
80 ̊C if the mass of the pan is 0.5 kg and its specific heat capacity is 480 J/kg ̊C.
Q.21 How much heat is required to raise the temperature of 150 g of a lump of iron from
25 ̊C to 150 ̊C? (Specific heat capacity of iron = 480 J/kg ̊C).
Q.22 Due to winter season the temperature of water is 5 ̊C. If 20 liters of water has to be
heated to 35 ̊C for taking both. Calculate the amount of heat required for it. (The specific
heat capacity of water id 4200 J/kg ̊C and the mass of liter of water is 1 kg)
Q.23 Heat of 1000 Joule is released while a lump of iron mass 2 kg at 90 ̊Cis cooled to
15 ̊C. Calculate the specific heat capacity heat capacity of iron.
Q.24 How much heat must be added to raise the temperature of 800 gm of water from
10 ̊C to 90 ̊C? The Specific heat capacity of water is 4200 J/kg ̊C.
Q.25 If 3.36 × 10 6 joule of heat energy is required to change the temperature of alcohol
from 15 ̊C to 75 ̊. Calculate the mass of alcohol. Specific heat capacity of alcohol is 2400
J/kg ̊C.
Q.26 If 2.2 × 10 5 joule of heat energy is given to 2 kg of water, calculate the increase in
temperature. Specific heat capacity of water is 4200 J/kg ̊C.
Q.27 A piece of iron having mass 20 kg and temperature 200 ̊C is dropped into 10 kg of
water having 25 temperatures. Calculate the final temperature of the mixture. Specific
heat capacity of iron is 470 J/kg ̊C and Specific heat capacity of water is 4200 J/kg ̊C
CHAPTER 5
Light
Q.1 What is a convex lens? Draw a neat diagram showing a convex lens.
Q.2 What is a concave lens? Draw a neat diagram showing a concave lens.
Q.3 Show with the help of a scaled ray diagram, that the image of an object laced at 2F of
a convex lens is produced at 2F on the other side of the lens.
Q.4 How convex lens does enlarge and make the image erect of an object? Show by
drawing labeled ray diagram.
Q.5 What is shot sightedness? What type of lens to be used in spectacle to correct this
defect?
Q.6 What type of defect is found in the given diagram of the eye? Draw a diagram to
show how this defect can be corrected.
Q.7 Given below is the diagram of an eye with defect of vision. Answer the following
questions:
i.
ii.
What defect of vision is found in the eye?
Which lens is to be used to correct this defect of vision?
Q.8 Study the given diagram and answer the following questions:
i.
ii.
iii.
iv.
Copy the diagram and complete the ray diagram.
Why does a lens refract light?
In which defect of vision is such lens used?
Draw the diagram showing the correction of this defect.
Q.9 Write any three uses of convex lens?
Q.10 Why convex lens is called converging lens?
Q.11 Why concave lens is called diverging lens?
Q.12 Write down the uses of concave lens.
Q.13 Short sightedness cannot be corrected by the use of convex, why?
Q.14 Draw a ray diagram to show the function of compound microscope. Write difference
between the nature of images formed by eye lens and objective lens.
Q.15 Complete the diagram and state natures of the image formed.
Q.16 If a student on the last bench of the class cannot read the letters written on the black
board clearly, then
i.
Draw a diagram to the defect of his eye.
ii.
Give reason of the defect.
iii. Why is concave lens used to remove such defect?
Q.17 Write any two differences between telescope and compound microscope.
Q.18 Draw a ray diagram of the image formed by the lens if a microscope. Explain with
reason.
Q.19 Redraw the given diagram and complete the ray diagram. Also write four natures of
the image thus formed
Q.20 Objectives lens of telescope is made wider than that of microscope. Explain with
reason.
Q.21 Draw a ray diagram to show the position and nature of the image of an object placed
in between the principal focus and the optical centre of a concave lens.
Q.22 Redraw the given diagram and complete the ray diagram. Also write four natures of
the image so formed.
Q.23 What is the function of iris of an eye?
Q.24 Draw labeled diagram to show the way of correcting myopia.
Q.25 Sita is wearing spectacles of power +з.5 D. what is the defect of her eye.
Q.26 Define the following terms:
i.
Centre of curvature
ii.
Principal focus
iii. Focal length
Q.27 What do you mean by aperture and radius of curvature?
Q.28 What is focusing? Why is it done?
Q.29 What is image? Name two types of image.
Q.30 Mention any two differences between real image and virtual image.
Q.31 What do you mean by real imaging? Name the type of lens that forms real image.
Q.32 Draw a neat and labeled ray diagram showing the image formed by a convex lens
when the object is placed between optical centre and focus. Also, write down the
characteristics of the image formed.
Q.33 Draw a neat and labeled ray diagram showing the image formed by a convex lens
when the object is laced.
i.
At focus (F)
ii.
Between F ad 2F. Also, write down the characteristics of the image formed.
Q.34 Draw a neat and labeled ray diagram showing the image formed by a convex lens
when object is
i.
At 2F
ii. Beyond 2F
Q.35 Draw a neat and labeled ray diagram showing the image formed by convex lens
when object is
i.
At infinity such that the rays coming from it are parallel to the principal axis
ii.
At infinity such that the rays coming from it are no parallel to the principal axis.
Q.36 Draw a neat and labeled ray diagram showing the image formed by a concave lens
when object is
i.
At infinity such that rays coming from it are parallel to the principal axis.
ii.
At infinity such that rays coming from it are not parallel to the principal axis.
Also, mention the characteristics of the image formed.
Q.37 Differentiate between the images formed by convex lens and concave lens.
Q.38 What do you mean by power of a lens? Write down the formula and unit of power
of a lens.
Q.39 Define one dioptre power of a lens. Name the factor on which the power of a lens
depends.
Q.40 How is the power of a combination of lenses determined? Explain with an example.
Q.41 Why is the combination of lenses done? Name any three instruments in which
combination of lenses is done.
Q.42 What do you mean by lens formula? Write down the lens formula.
Q.43 What do you mean by ‘magnification’ produced by lenses? Give its formula.
Q.44 What kind of lens can form
i.
Erect and magnified image?
ii.
Inverted and diminished image?
iii. Erect and diminished image?
iv.
Inverted and magnified image?
Q.45 State the nature of a lens having a power of (a) + 5D (b) – 8D.
Q.46 Which lens is used for projecting the images on the screen? If the image formed by a
lens is of the same size as that of the object, then state the nature and position of the
image?
Q.47 What are optical instruments? Give examples.
Q.48 What is photographic camera? State the principle of construction of photographic
camera.
Q.49 Describe the construction of a photographic camera with a diagram. Also draw the
ray diagram showing the image formed by camera.
Q.50 How is a photograph prepared after producing image in the photographic film?
Q.51 Describe the structure of the human eye with a neat diagram.
Q.52 Write down the working mechanism of human eye.
Q.53 What do you mean by accommodation? Write down the range of the vision of the
normal human eye.
Q.54 Define ‘far point’ and ‘near point’.
Q.55 An object placed at a distance of less than 25 cm cannot be seen by normal human
eye. What is the reason behind it?
Q.56 What do you mean by the defect of vision? Name various types of defects of
visions.
Q.57 What is myopia? Write down the causes of such defect of vision. Draw a neat
diagram showing such defect of vision.
Q.58 How is myopia corrected? Explain with ray diagram.
Q.59 What is long-sightedness corrected? Explain with ray diagram.
Q.60 What is hypermetropia? How is it caused? Draw a neat ray diagram showing such
defect of vision.
Q.61 Mention any three similarities between a photographic camera and a human eye.
Q.62 What is a microscope? How is it possible to see the details of very tiny objects
through the microscope?
Q.63 Mention any four differences between a photographic camera and a human eye.
Q.64 With the help of a ray diagram, describe the formation of image in simple
microscope.
Q.65 Describe the construction and working of a compound microscope with a neat and
labeled diagram.
Q.66 What is a telescope? Name the two types of telescope and define each of them
Q.67 Describe the construction and working principle of an astronomical telescope with a
neat and labeled ray diagram.
Q.68 Give reason:
i.
The objective lens of a compound microscope has a small aperture.
ii.
The objective lens of a astronomical telescope has a larger aperture and the eye-
piece has a smaller aperture.
Q.69 If lighting candle is placed at the distance of 4 cm from a convex lens having the
focal length of з cm, draw a ray diagram to show the formation of image. Calculate the
magnification of the lens.
NUMERICAL PROBLEMS
Q.1 Calculate the power of a convex of focal length 50 cm.
Q.2 The power of a lens is 2.5 D. Calculate the focal length of the lens.
Q.3 Two lenses of powers +5D and -2D are placed in a close contact. Calculate the power
and focal length of the combination.
Q.4 A convex lens of focal length 20 cm is placed at a distance of 24 cm from a wall.
How far (from the lens) should an object be placed so as to form its real image on the
wall?
Q.5 An object of 8 cm height is placed at a distance of 20 cm from a convex lens of focal
length 40 cm. find the position, nature and size of the image.
Q.6 An object kept 30 cm far from a lens gives a virtual image at a distance of 10 cm in
front of the lens. Calculate the focal length and magnification of the lens. Is the lens
convex or concave? Give reasons to justify your answer.
Q.7 An object placed 1 m away from the lens forms an erect image exactly half the size
of the object. Determine the focal length of the lens. Also, state the type of lens.
Q.8 Calculate the power of a concave lens of focal length – 25 cm.
Q.9 An object is placed 30 cm away from a convex lens. If the image distance is 15 cm,
calculate the focal length, power and magnification.
Q.10 Nisha cannot see clearly objects beyond 50 cm. calculate the focal length of the lens
that would enable her to see distant objects clearly.
CHAPTER 6
Current Electricity And Magnetism
Q.1 What is current electricity? Write down its SI unit.
Q.2 What do you mean by open circuit?
Q.3 Define a closed circuit with a suitable diagram.
Q.4 Why is combination of cells done? Name its types.
Q.5 Define series combination of cells.
Q.6 What do you mean by parallel combination of cells?
Q.7 Draw a closed circuit diagram by showing a load, a switch and 4 cells each of 1.5 V
combined in a series.
Q.8 What is a load? What do you mean by series combination of loads?
Q.9 Why are cells connected in parallel?
Q.10 Why are cells combined in a series?
Q.11 Write down three laws of Faraday’s electromagnetic induction.
Q.12 What is an electric circuit? How should cells be combined to increase the
electromotive force? Fuse is always connected in the live line, why?
Q.13 What is fuse? Write the type of combination of cells in the given circuit.
Q.14 What is the fundamental difference between alternating current (AC) and direct
current (DC)? What type of connections is made is household wiring? Write an
advantage of that type of connection. What is fuse? Give its one advantage.
Q.15 What is motor effect of electricity?
Q.16 Write down Fleming’s right hand rule. The use of a miniature circuit breaker (MBC)
is better than a fuse, why? Draw a neat and labeled diagram of an electric bell.
Q.17 Write down one advantage of each of the following
Electromagnet, fuse and main switch
Q.18 Name two metal used to make fuse wire. Why fuse wire is always used to live line
of an electric circuit?
Q.19 What is meant by 1 kWh? Express it in joule.
Q.20 Define the term electromagnetic induction. Name an appliance which produces
electricity on the basis of this principle. How is it induced e.m.f. related with magnetic
flux?
Q.21 The voltage of which type of current is changed by transformer? Why is core of
transformer laminated?
Q.22 Give two ways to increase the strength of an electromagnet.
Q.23 If the wire ‘AB’ is moved in the direction shown, in which direction does the current
flow? State two ways to increase the induced current in generator.
Q.24 State the relation between induced e.m.f and the rate of flux change in a bicycle
dynamo. Suggest other two different ways by which the output of the dynamo can be
increased.
Q.25 Why is the earthing done? Give two differences between step up and step down
transformer.
Q.26 What is generator? Write any two ways of increasing the magnitude of current in the
generator.
Q.27 Name the type of combination of bulbs in the given circuit. Define the type of
connection of bulbs. Write one advantage of this type of connection. What differences
will you see in the brightness of the bulbs if their number is reduced?
Q.28 What is dynamo? State the Fleming’s left hand rule.
Q.29 What is phase wire and neutral wire?
Q.30 Define electric circuit and solenoid.
Q.31 Why does a fluorescent lamp of 40 watt fives more light than a bulb of 40 watt?
Q.32 Write three reasons for using an electromagnet widely.
Q.33 Study the given circuit diagram and answer the following questions:
i.
ii.
Q.34
i.
ii.
What happens to the brightness of bulb when the number of cells is reduced?
Why?
Write down one advantage and one disadvantage of the above circuit.
Write any two differences between filament lamps and fluorescent lamp.
How is the electric current induced in the secondary coil?
Q.35 State four methods to increase the magnitude of current generated from a generator.
Q.36 Tungsten filament is used in electric bulb. Why?
Q.37 Draw a three dimensional diagram to show the direction of induced current, motion
of the conducting wire and the direction of magnetic field.
Q.38 What is motor effect? Write the working principle of a transformer.
Q.39 Which metal is used to make heating element and why?
Q.40 What will happen if a filament lamp is filled with air? Give reasons. Draw a labeled
diagram of a step up transformer.
Q.41 Draw a circuit diagram to light two bulbs of 3 volt each with full brightness with the
help of two cells of 1.5 volt each. What is the name of such connection of bulbs?
Q.42 What is the type of connection of bulb in domestic circuit? Give two advantages of
this connection.
Q.43 Give a difference between generator and electric motor.
Q.44 What is electromagnetic induction?
Q.45 How does a dynamo produce electric current? Explain it in brie. The number of
turns of primary coil and the number of turns of secondary coil in a transformer are never
made equal, why?
Q.46 Name the type of transformer which is used to play the radio with 12 volt in the
electric line of 240 volt.
Q.47 Study the given circuit diagram and answer the following questions.
i.
ii.
Name the type in which the bulbs are connected in the circuit. Define the type of
connection of bulbs.
What differences will you see in the brightness of the bulbs if their number is
reduced?
Q.48 Answer the following questions with the help of diagram given:
i.
ii.
Name the type of combination of cells.
Which type of combination of cells has more current?
Q.49
a. Sketch the symbols for electric resistor, voltmeter and a cell.
b. Sketch diagram to show how two resistors of 100 ohm resistance each
should be connected to produce the total resistance of (a) 50 and (b)
200
Q.50 Many electrical appliances are earthed, why?
Q.51 Explain with reasons:
i.
Fuse is an important in a domestic circuit.
ii.
When electric current is passed through a filament, it glows with bright light due
to heating but it doesn’t happen in other wires.
Q.52 Draw a labeled diagram of the electroplating copper on iron nail and also write
down the chemical reaction that occurs in the copper plate and iron nail.
Q.53 Sketch a closed circuit diagram containing a voltmeter, an ammeter, a cell and a
load. Also, indicate the direction of the current floe in the circuit.
Q.54 In terms of energy conversion, what is the difference between a dynamo and an
electric motor?
Q.55 What happens if alternating current is passed into the coil of the dynamo?
Q.56 A silver ring is to be coated with gold. An open circuit is the given in the diagram
needed. Answer the questions related with it:
i.
ii.
iii.
Redraw the diagram with battery connected properly in the circuit.
Which electrolyte should be used for electroplating?
If the electrode ‘E’ is a piece of gold, what will be the condition after
electroplating process?
Q.57 What is the meaning of the saying ‘the frequency of electricity distributed in
Kathmandu is 50 Hz’?
Q.58 What is transformer? Write down the type of transformer in which turning of wire in
secondary coil is less than that of primary coil.
Q.59 Write with suitable example what is meant by heating effect of electricity.
Q.60 Draw a neat and labeled diagram of the process of purification of copper with the
help of electricity. What happens when magnitude of current is increased in it?
Q.61 Write down the reason of not using tungsten metal wire in the heater.
Q.62
i.
What happens when pure copper plate is kept instead of iron nail in the given
figure?
Where does copper ion move when there occurs ionization of copper sulphate and
ii.
why?
Q.63 Answer the following questions with the help of diagram:
i.
ii.
iii.
Name the parts X and Y.
What happens if copper wire is used in place of X?
What happens when the pole of battery is reversed?
Q.64 Mention any one difference between:
i.
Electrode and electrolyte
ii.
Voltameter and voltmeter
Q.65 What do you mean by rating of a fuse? How is it done?
Q.66 Differentiate between
i.
An electromagnet and a permanent magnet
ii.
Filament lam and fluorescent lamp
Q.67 Give reasons
i.
Mercury vapor is filled in a fluorescent lamp.
ii.
Inner wall of a fluorescent lamp is coated with fluorescent powder.
Q.68 Who discovered the fact that electricity can induce magnetic effect? What is
galvanometer? Draw a neat diagram showing the process of electromagnetic induction.
Q.69 What is electric motor? Name any four equipments in which electric motor is used.
Q.70 Write down the applications of heating effect of current.
Q.71 What is heating element? Write two differences between nichrome wire and fuse
wire.
Q.72 What do you mean by lighting effect of current? Write its application. The tungsten
filament becomes white hot while passing current through it but the copper wire
connecting the filament does not. Why?
Q.73 Draw a neat and labeled diagram showing the electrolysis of water. Also, write the
chemical reaction that takes place at anode and cathode.
Q.74 What is electroplating? Draw a neat diagram showing the electroplating of copper in
an iron nail. Also, write down the reaction that takes pace at cathode and anode.
Q.75 Mention any three points to be remembered while electroplating.
Q.76 Write down the advantage of electroplating.
Q.77 What do you mean by magnetic effect of current? Name the scientist who
discovered this effect. Draw a neat figure to show this effect.
Q.78 What is heating element? Which heating element is used in a heater? Write any two
differences between filament lamp and fluorescent lamp.
Q.79 Lamp is lighted in the running bicycle by the help of dynamo, but it goes off when
bicycle is stopped, explain with reason. What type of connection is made in the domestic
circuit? Give any two methods to increase the magnitude of the current produced by a
generator. What is fuse?
NUMERICAL PROBLEMS
Q.1 If two irons with 750 watt each are used eight hours a month, how much tariff should
be paid. Cost of 1 unit of electricity is Rs. 7.
Q.2 If a transformer is connected to the 240 Volt AC mains and the number of turning of
primary coil in it is 2000, calculate the number of turnings in its secondary coil.
Q.3 Write the type of combination of cells in the given circuit. Calculate the power of the
bulb if 0.2 A current flows through the circuit.
Q.4 Ten electric bulbs of 100 watt each are used for 6 hrs and з electric heaters of 2 kW
each are used for 2 hrs. Calculate the total consumption of electricity for a day.
Q.5 The primary winding of a transformer is 1000 turns and it is supplied with 6A, 220V.
The output is 100V. Calculate (i) number of turns in a secondary coil and (ii) electrical
energy consumed (in kWh) by primary coil in 10 hours.
Q.6 What capacity of fuse should be used, if a heater of 0.8 kW is connected to the line of
220V?
Q.7 Four electric bulbs of 60Wpower each and a heater of 1000W power are used in a
home for 4 hours and 40 minutes daily respectively. Calculate the monthly cost of
electricity at the rate of Rs. 7.50 per unit. Calculate the main current when all these
appliances run together. (Take the voltage supply is 220V).
Q.8 Observe the given figure and answer the following questions:
i.
ii.
What type of transformer is this and why?
Calculate the number of turns in the secondary coil.
Q.9 An electric heater of 1500 watt is used for 2 hours daily. Calculate the number of
turns in secondary coil to give out a secondary voltage of 30V.
Q.10 Study the given diagram and answer the following questions:
Name the type of combination of cells in figure ‘a’ and ‘b’. Calculate total current
flowing in each circuit
Q.11 A transformer has primary voltage of 220V and primary winding of 800 turns.
Calculate the number of turns in secondary coil to give out a secondary voltage of 30V.
Q.12 If an iron of 1000 W, two bulbs of each 100 W, a television of 60 W and a radio of
40 are used in a house, what should be the capacity of use used? The voltage of the
supplied line is 220V.
Q.13 Study the given diagram and calculate the current flowing through the given circuit.
Q.14 The primary winding of a step down transformer has 770 turns and it is supplied
with 6A, 22oV mains. The secondary windings produce 110V. Calculate the amount of
electric energy consumed (in kWhr) by the primary winding of the transformer in 1 day.
Q.15 The number of turns in the primary winding of a certain transformer is 150 times
more than that in the secondary winding. Calculate the input e.m.f. in the primary
winding if the e.m.f. generated in secondary winding is 220V AC.
Q.16 In a house, a heater of 1500W, a refrigerator of 1000W, a television of 80W, 3 bulbs
of 60W each and an iron of 1000W are used. Calculate the rating of fuse in the supply of
220V AC to run all the appliances safely.
Q.17 Study the given figure and answer the following questions:
i.
ii.
iii.
Which type of transformer is this and why?
Which function does the core in transformer?
Calculate the voltage produced in the secondary coil.
Q.18 If a 1000 cw heater is to be operated in 220V mains, what must be the rating of the
fuse
to
be
used
with
the
heater?
Q.19 Ten electric bulbs of 100 watt each and two electric heaters of 1000 watt each are
used for 6 hours continuously. Calculate the unit of electricity consumed.
Q.20 An electric kettle rated 22o V and 2.2 kW works for 3 hours. Find the energy
consumed and the current drawn by it.
Q.21 A bulb of 100 watts and a heater of 1000 watts are used for 3 hours daily in a room.
What will be the increase in the reading of electric sub-meter of that room after 15 days?
Q.22 The number of turns in the primary winding of a certain transformer is 150 times
more than that in the secondary winding. Calculate the input emf in the primary winding
if the emf generated in the secondary winding in 220 V AC.
Q.23 What is the amount of current needed for a fluorescent lamp of 40 W connected to a
source of 220V?
Q.24 A transformer is of 220V primary voltage and 770 turns of primary coil. How many
turns of secondary coil will be needed in order to produce 120 V from that transformer?
Q.25 A transformer is of 220V primary voltage and 1000turns of primary coil. How many
turns of secondary coil will be needed in order to produce 110 V from that transformer?
Q.26 An electric heater draws a current of 10 A from main line of 220 V, then what will
be the total cost for using it in one month. The cost of electricity is Rs. 6 per unit.
Q.27 A domestic wiring has a fuse of 5A. What is the maximum number of 100 watt bulb
that can be used in the supply of 220V?
Q.28 A transformer has 220V in primary coiling with 200 turns in it. What will be the
number of turning in secondary coiling to get a voltage of 33V?
Q.29 What will be the capacity of a fuse to operate a heater of 0.8 kW with 220 V main
supplies?
Q.30 The number of turns in the primary winding of transformer is 200 times more than
that in the secondary winding. Calculate the input emf in the primary winding if emf
generated in the secondary winding in 220 volt AC.
Q.31 Which type of transformer is given in the picture and what is used to laminate its
core? Write any one application. Calculate the voltage produced in secondary coil.
Q.32 An electric iron of 750W is connected in 220V main line, what should be the
capacity of the fuse?