ICSE Class 9 Physics Sample Question Paper 8 with Answers

ICSE Class 9 Physics Sample Question Paper 8 with Answers

Section -1
(Attempt all questions from this section)

Question 1.
(a) The bob of a simple pendulum is made of wood. What will be the effect on the time period if an identical bob of aluminium replaces the wooden bob ?
(b) (i) The linear distance moved by the screw, when it is given one complete rotaion is
equal to the distance between two consecutive threads, as measured along the axis of the screw. This distance is called ………………….. the of the screw.
(ii) The least count of a screw is defined as the distance moved by the screw on the main scale when the screw is given ………………….. complete revolution/s.
(c) What happens when you shake a wet piece of cloth ? Explain your observation.
(d) A bag of sugar weighs ‘W’ at some place on the equator. If this bag is taken to the poles, will it weigh the same, more or less ? Give a reason for your answer.
(e) A body of mass 500 g is at rest on a frictionless surface. Calculate the distance travelled by it in 10 s when acted upon by a force of 10^-2 N.
Answer:
(a) There is no change in the time period of the simple pendulum because though the wooden bob is replaced by the aluminium bob, the effective length of the pendulum remains the same. Since the time period of a simple pendulum does not depend on the mass of the bob, it remains unaltered.

(b) (i) Pitch, (ii) One

(c) Initially, the piece of cloth and the loose water in it are in a state of rest. When the cloth is shaken, it is suddenly set into motion. However, the water in it, on account of inertia of rest, continues its state of rest. Thus, water comes out of the cloth in the form of fine particles.

(d) The bag of sugar will weigh more at the poles. The reason for this is, the polar radius of the earth is less than the equatorial, radius of the earth. The acceleration due to gravity is inversely proportional to the square of the radius of the earth. Hence, its value at the poles is greater than its value at the equator. Since weight is the product of mass and acceleration due to gravity, therefore, the bag of sugar will weigh more at the poles.

(e) Given : m = 500 g = 0.5 kg, t = 10 s , F = 10^-2 N 0.01 N, u = 0
Using  F – ma,
we have,

Question 2.
(a) Why are two holes made in an oil tin to remove oil from it ?
(b) A piece of ice is gently placed on the surface of water filled in a glass tumbler, so the water rises to the brim. What will happen to the level of water when the ice melts ? Will the water overflow ? If not, explain with reason.
(c) State two advantages of L.P.G.
(d) Why are taps left dripping in sub-zero temperature during winter ?
(e) The base of a cylindrical vessel measures 300 cm². Water is poured into it upto a depth of 6 cm. Calculate the pressure and thrust on the base. (Take density of water = 103 kg m^-3 and g = 10 ms^-2.)
Answer:
(a) If a single hole is made in the oil tin, the oil will not flow out because the pressure inside the tin becomes less than the atmospheric pressure. In order to force oil out, two holes are made. Thus, air enters from one hole, exerts pressure on the oil, and forces ìt out from the other hole.

(b) Since ice floats in water, its weight is equal to the weight of displaced water. Suppose ice weighs ‘m’ gf, then the weight of displaced water will also be ‘m’ When the ice melts, m gf of water is obtained which is equal to the weight of displaced water, so there will be no change in the level of water, and the water does not overflow.

(c) Two advantages of L.P.G. are as follows :

• It is easy to handle and convenient to store.
• It does not produce harmful gases on burning.

(d) The taps are left dripping during winter to provide sufficient space for expansion of freezing water due to its anomalous expansion. If this is not done, the freezing water will exert large pressure on the tap and there are chances that it may burst.

(e) Given : h = 6 cm = 6 x 10^-2 m, A = 300 cm² = 3 x 10^-2 m² , density of water= 1000 kgmr³, g = 10 m/s²
We know,
Pressure, P = hρg
= 6 x 10^-2 x 1000 x 10
= 600 Pa.
Thrust, F = P x A
= 600 x 3 x 10^-2 = 18 N

Question 3.
(a) Can a plane as well as a convex mirror produce real image if the object is virtual ? Explain.
(b) Complete the following sentences :
(i) A ray of light parallel to the principal axis of a convex mirror seems to come from
the after reflection.
(ii) A concave mirror forms an erect image when the object is placed between the focus
and the
(c) State the laws of reflection of light.
(d) What is the range of frequencies associated with (i) Infrasound, and (ii) Ultrasound ?
(e) A submarine emits a sonar pulse, which returns from an underwater cliff in 1.2 s. If the speed of sound in salt water is 1460 ms^-1, how far away is the cliff ?
Answer:
(a) Yes, a real image can be obtained from both plane mirror and convex mirror if the object is virtual and behind the mirror. This can be done by making a converging beam of light fall on the mirror. The converging beam forms a virtual object behind the mirror, producing a real image in front of the mirror.

(b) (i) Focus
(ii) Pole

(c) The laws of reflection of light are :
(1) The angle of incidence (i) is equal to the angle of reflection (r).
(2) The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane.

(d) (i) Infrasound waves are between the frequencies 1 to 20 Hz.
(ii) Ultrasound waves are of the frequencies above 20000 Hz.

(e) Given : t = 1.2 s; ν – 1460 ms^-1, S = ?

Question 4.
(a) Define electric current. Name its S.I. unit.
(b) Fill in the blanks :
A cell cannot be recharged whereas a cell can be recharged.
(c) Name two types of cells.
(d) What do you mean by magnetic field of a magnet ?
(e) Define magnetic pole of the Earth.
Answer:
(a) Electric current is defined as the rate of flow of charge through a certain cross-section of a conductor in a particular direction. Its S.I. unit is ampere (A).
(b) Primary, secondary.
(c) Two types of cells are — Primary cells and secondary cells.
(d) The region around a magnet in which its magnetic force can be experienced by another magnetic substance is called magnetic field of the magnet.
(e) The point on the earth where a magnetic needle points vertically is called the magnetic pole.

Section – II
(Attempt any four questions from this section)

Question 5.
(a) A large truck and a car, both moving with speed V, have a head on collision and both of them come to halt after that. If the collision lasts for 10 s,
(i) Which vehicle experiences the greater force of impact ?
(ii) Which vehicle experiences the greater momentum change ?
(iii) Which vehicle experiences the greater change in acceleration ?
(b) The acceleration due to gravity at the moon’s surface is 1.67 ms^-2. If the radius of the moon is 1.74 x 106 m, calculate the mass of the moon. Use the known value of G.
(c) The main scale of a vernier calliper is caliberated in mm and 19 divisions of main scale are equal in length to 20 divisions of vernier scale. In measuring the diameter of a cylinder by this instrument, the main scale reads 35 divisions and 5th division of vernier scale coincides with a main scale division, find the (i) least count, (ii) diameter of the cylinder.
Answer:
(a) (i) Both the vehicles experience same force of impact as action and reaction are equal and opposite in both cases.
(ii) The truck experiences a greater change in momentum on account of its greater mass.
(iii) The car experiences greater change in acceleration as force remaining same, acceleration is inversely

Question 6.
(a) Mention any three areas where solar cells are being used as a source of energy.
(b) State three limitations of solar energy.
(c) A balloon of volume 50 m³ is filled with hot air of density 0.4 kg m². If the weight of the fabric of the balloon is 12 kgf and equipment ‘P’ is attached to it, such that balloon is in the state of equilibrium, calculate (i) weight of hot air, (ii) weight of hot air, balloon and equipment, (iii) upthrust, and (iv) weight of equipment. (Density of normal air = 1.3 kg / m³)
Answer:
(a) Three areas where solar cells are being used as energy are :
(1) Artificial satellites
(2) Radio or wireless transmission
(3) Traffic lights.

(b) Three limitations of solar energy are as follows :
(1) Solar energy is not available at a constant rate due to clouds, wind, haze, etc.
(2) Solar energy is not available at night uniformly.
(3) Solar energy may not be available at all places on the earth.

(c) (i) Weight of hot air = Volume of balloon x Density of hot air x g
= 50 x 0.4 x g = 20 kgf

(ii) Weight of (Hot air + Balloon + Equipment)
= 20 + 12 + P = (32 + P) kgf

(iii) Upthrust = Weight of air displaced
= Volume of balloon x Density of air x g = 50 x 1.3 x g = 65 kgf

(iv) By law of floatation, we have
32 + P = 65
P = 65 – 32 = 33 kgf.

Question 7.
(a) Define the following terms related to spherical mirrors :
(i) Principal axis, (ii) Focal plane, (iii) Focal length.
(b) An object of size 5 cm is placed at a distance of 24 cm in front of a concave mirror of focal length 16 cm. At what distance from the mirror should a screen be placed so as to obtain a sharp image of the object ? Find the nature of the image.
(c) State four uses of concave mirror.
Answer:
(a) (i) The straight line passing through the pole and the centre of curvature of the mirror is called the principal axis.
(ii) A plane drawn perpendicular to the principal axis and passing through the principal focus is called the focal plane.
(iii) The distance between the pole and the focus is called the focal length. It is represented by

(b) Given : h = 5 cm, u = – 24 cm, f = – 16 cm, v = ? , h’ = ?

The image is formed 48 cm in front of the mirror. Thus, the image is real and inverted. Thus, the screen should be held 48 cm in front of the mirror.

(c) Concave mirrors are used for the following purposes :
(i) Reflecting mirror for projector lamps.
(ii) In torches and head lights.
(iii) In a shaving mirror, and
(iv) It is used to concentrate sunlight in solar farms.

Question 8.
(a) What are mechanical or elastic waves ? Name its two types.
(b) A body is vibrating 60000 times in one minute. If the velocity of sound in air is 340 ms^-1,
find (i) frequency of the vibration in Hz
(ii) wavelength of the sound produced. Also,
(iii) ………. can this sound be heard by human beings ?
(c) State four uses of ultrasound.
Answer:
(a) A mechanical wave is a distubance that travels through some material medium or substance called the medium of the wave.
It has two types : (1) Transverse waves and (2) Longitudinal waves.

(b) Given : Number of vibrations = 60000, time (t) = 1 min = 60 s, velocity (ν) = 340 ms^-1

(iii) Here, f = 1000 Hz, hence it can be heard by human beings, (c)
(c) Ultrasound is used for the following purposes :
(1) To monitor the growth of a foetus (unborn baby).
(2) To investigate the internal organs of human body.
(3) To break kidney stones into fine grains.
(4) To remove brain tumour.

Question 9.
(a) (i) What is a secondary cell ?
(ii) State two advantages of a secondary cell over a primary cell.
(b) (i) What do you mean by efficient use of energy ?
(ii) How can energy efficiency be achieved ?
(c) Draw the circuit symbols of the following :
(i) Cell
(ii) Fixed resistance
(iii) Switch
(iv) Ground.
Answer:
(a) (i) A secondary cell is one in which chemical energy is converted into electrical energy but they do so only when they are charged by passing current through them by some source.
(ii) Advantages of secondary cell over primary cell are :
(1) A secondary cell can be put to use again and again by recharging it; while a primary cell once discharged, cannot be charged again.
(2) The internal resistance of a secondary cell is less than that of the primary cell. As such, a much larger current can be drawn from a secondary cell than that can be drawn from a primary cell.

(b) (i) Efficient use of energy refers to the reduction of cost and amount of energy used in order to provide various products and services.
(ii) Energy efficiency can be achieved by adopting more efficient eco-friendly technologies and processes.

Question 10.
(a) (i) Define resistance.
(ii) A cell is connected to a bulb which develops a potential difference of 6 volt across it. The current in circuit is measured to be 2 ampere. Find the resistance offered by the filament of bulb to the flow of current.
(b) Draw a neat labelled diagram of an electric bell.
(c) State four evidence to show the existence of earth’s magnetic field.
Answer:
(a) (i) The obstruction offered to the flow of current by the wire is called its electrical resistance.
(ii) Given : V = 6 volt, I = 2 ampere
Resistance of filament of bulb, R =y \(\begin{aligned}
\mathrm{R} &=\frac{\mathrm{V}}{\mathrm{I}} \\
&=\frac{6}{2}=3 \mathrm{ohm}
\end{aligned}\)

(b)

(c) The existence of earth’s magnetic field is based on the following facts :
(1) An iron rod buried inside the earth along north-south direction becomes a magnet.
(2) A magnetic needle rests with its geometric axis making different angles with horizontal when suspended at different places on earth.
(3) A freely suspended magnetic needle always rest in geographic north-south direction.
(4) Neutral points are obtained on plotting the field lines of a magnet where the net magnetic field is zero.

ICSE Class 9 Physics Question Papers with Answers