 # ICSE Class 10 Physics Question Paper Solution 2015

The detailed solutions for the class 10 Physics 2015 question paper are provided here. Students must practice the past year 2015 questions to get an idea on types of questions asked in the exam and overall difficulty level of the paper. After solving the Physics paper, students must evaluate their performance from the answers provided in the ICSE Class 10 Physics Question Paper Solution 2015. They should find out their mistakes and work on them so that they score more marks in the board exam.

The ICSE Class 10 Physics 2015 exam started at 11 am and students were allotted 2 hours of time duration to finish the paper. They can download the ICSE Class 10 Physics Question Paper Solution 2015 PDF from the link below. They can refer to it anytime while studying or doing the revision.

#### Students can have a look at the ICSE Class 10 Physics Question Paper Solution 2015 below:                 ### Topics Found Confusing and Difficult in Physics 2015 Question Paper

We have listed the difficult topics which students found tricky and confusing while attempting the 2015 Physics Science Paper 1.

• Cases of inter conversion of energy.
• Concept of work. Work done for different angles between force and displacement.
• Numerical problems based on p=f.v and machines.
• Interpretation of graphs and slopes.
• Vibration in a stretched string.
• Cases of resonance, forced vibrations, free vibrations, etc.
• Safe limit of sound level for humans.
• Numerical problems on “Heat”
• Difference between heat capacity, SHC and SLHC.
• Similarities between A.C generator and D.C motor.
• Cathode ray tube.
• Mass number and atomic number.

## ICSE Class 10 Physics (Science Paper 1) Question Paper 2015 With Solution

### Question 1:

(a) When a body is placed on a table top, it exerts a force equal to its weight downwards on the table top but does not move or fall. (i) Name the force exerted by the table top.

(ii) What is the direction of the force?

(b) (i)

Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.

(ii) On reversing the direction of the current in a wire, the magnetic field produced by it gets ————–.

(c) (i)

On what factor does the position of the centre of gravity of a body depend?

(ii) What is the S.I unit of the moment of force?

(d) Name the factors affecting the turning effect of a body.

(e) (i) Define equilibrium.

(ii) In a beam balance when the beam is balanced in a horizontal position, it is in ______ equilibrium.

(a) (i) Normal reaction force

(ii) Vertically upwards.

(b) (i) Thickness of glass slab / angle of incidence/refractive index of glass/colour of light/ wave length of light ( Any one)

(ii) reversed in direction

(c) (i) Shape of body/distribution of mass of body.

(ii) Nm.

(d) (i) magnitude of the force applied .

(ii) Perpendicular distance of line of action of the force from the axis of rotation./ Moment arm / perpendicular distance between point of application of force and point of rotation (Any one)

(e) (i) When a number of forces acting on a body produce no change in its state of rest or motion, the body is said to be in equilibrium.

(ii) Static.

### Question 2:

(a) How is work done by a force measured when the force :

(i) is in the direction of displacement

(ii) is at an angle to the direction of displacement.

(b) State the energy changes in the following while in use:

(i) Burning of a candle.

(ii) A steam engine.

(c) (i) A scissor is a _______ multiplier.

(ii) 1 kWh = _______ J.

(d) Explain the motion of a planet around the sun in a circular path.

(e) Rajan exerts a force of 150 N in pulling a cart at a constant speed of 10 m/s. Calculate the power exerted.

(a)

(i) W = F X S

(ii) W = F X S Cos θ.

(b) (i) Chemical energy to Light energy and heat energy.

(ii) Chemical energy to Heat energy to Mechanical energy

(c)

(i) Speed

(ii) 3.6 x 106 J.

(d) A planet moves around the sun in a nearly circular path for which the gravitational

force of attraction on the planet by the sun provides the centripetal force.

(e) P = F X V

= 150 X 10

= 1500 W

### Question 3:

(a) (i)Give the expression for mechanical advantage of an inclined plane in terms of the length of an inclined plane.

(ii) Name a common device where a gear train is used.

(b) The speed of light in glass is 2 x 105 km/s. What is the refractive index of glass?

(c) (i) Draw a graph between displacement and the time for a body executing free vibrations.

(ii) Where can a body execute free vibrations?

(d) (i) What happens to the resistivity of semi-conductors with the increase of temperature?

(ii) For a fuse, higher the current rating ______ is the fuse wire.

(e) (i) Name the high energetic invisible electromagnetic waves which help in the study of the structure of crystals.

(ii) State an additional use of the waves mentioned in part (e) (i).

(a) (i) M.A. = l/h

(ii) It is used in a clock or a watch

(b) Refractive index of glass = speed of light in vacuum / speed of light in glass

= 3 X 108 / 2 X 105 X 1000

= 1.5

(c) (i) (ii) in Vacuum.

(d) (i) Resistivity decreases with the increase of temperature

(ii) Thicker

(e) (i) X rays

(ii) to detect the fracture in bones.

### Question 4:

(a) Rishi is surprised when he sees water boiling at 115⁰ C in a container. Give reasons as to why water can boil at the above temperature.

(b) (i) Why does a current carrying, freely suspended solenoid rest along a particular direction?

(ii) State the direction in which it rests.

(c) Find the equivalent resistance between points A and B. (d) Give two similarities between an A.C generator and a D.C motor.

(e) (i) Why is a cathode ray tube evacuated to a low pressure?

(ii) What happens if the negative potential is changed on a grid?

(a) Because of the presence of impurity. ( salt )

More the impurity more will be the boiling point.

(b) (i) A current carrying freely suspended solenoid behaves like a bar magnet

(ii) Geographic north south direction

(c) (d) Both in an A.C generator and D.C motor a coil rotates in magnetic field between

the pole pieces of a powerful magnet / presence of carbon brushes/ presence of armature coil (any two)

(e) (i) to avoid collisions of electrons with the air molecules

(ii) The brightness of the pattern on the screen can be changed.

### Question 5:

(a) Draw a simplified diagram of a lemon crusher, indicating direction of load and effort.

(b) (i) Name the physical quantity measured in terms of horse power.

(ii) A nut is opened by a wrench of length 20cm. If the least force required is 2N, find the moment of force needed to loosen the nut.

(iii) Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.

(c) A block and tackle system has V.R. = 5.

(i) Draw a neat labelled diagram of a system indicating the direction of its load and effort.

(ii) Rohan exerts a pull of 150 Kgf. What is the maximum load he can raise with this pulley system if its efficiency = 75%?

(a) Lemon crusher

(b) (i) Power of the appliance.

(ii) Moment of force = Force x Moment arm

= 2 x 20/100

= 0.4Nm

(iii) Force exerted on the ball and the displacement of the ball are in opposite directions or they make 1800 with one another.

(c) (i) Correct diagram drawn with directions of load and effort shown correctly

(ii) Efficiency = M.A / V.R

75 / 100 = M.A / 5 M.A = 3 .75

3 .75 = Load / 1500 or 3.75 = Load / 150

### Question 6:

(a) (i) Where an object should be placed so that a real and inverted image of the same size as the object is obtained using a convex lens?

(ii) Draw a ray diagram to show the formation of the image as specified in the part a (i)

(b) (i) Why does the Sun appear red at sunrise?

(ii) Name the subjective property of light related to its wavelength.

(c) Jatin puts a pencil into a glass container having water and is surprised to see the pencil in a different state.

(i) What change is observed in the appearance of the pencil?

(ii) Name the phenomenon responsible for the change.

(iii) Draw a ray diagram showing how the eye sees the pencil.

(a) (i) At 2F1 or centre of curvature

(ii) A ray shown parallel to the principal axis and passing through F2.

A ray shown passing through optical centre and moving undeviated.

Both rays drawn correctly.

Real image shown correctly.

(b) (i) At sunrise light has to travel longest distance in atmosphere, blue light gets

Scattered more and is lost.

Red Light has long wavelength, scatters the least and reaches the observer.

(ii) Colour of light

(c) (i) The pencil will be seen bent.

(ii) Refraction of light.

(iii) Two rays correctly drawn.

(iv) Image shown correctly.

### Question 7:

(a) (i) State the safe limit of sound level in terms of decibel for human hearing.

(ii) Name the characteristic of sound in relation to its waveform.

(b) A person standing between two vertical cliffs and 480 m from the nearest cliff shouts. He hears the first echo after 3s and the second echo 2s later. Calculate:

(i) The speed of sound.

(ii) The distance of the other cliff from the person.

(c) In the diagram below, A, B, C, D are four pendulums suspended from the same elastic string PQ. The length of A and C are equal to each other while the length of pendulum B is smaller than that of D. Pendulum A is set into a mode of vibrations. (i) Name the type of vibrations taking place in pendulums B and D?

(ii) What is the state of pendulum C?

(iii) State the reason for the type of vibrations in pendulums B and C.

(a) (i) Safe limit of sound level – upto 120 db

(ii) Quality of sound waves

(b) (i) V = 2 distance / time

= 2 X 480 / 3

= 320 m / s

(ii) Distance of the other cliff = (Velocity X Time ) / 2

= ( 320 X5) / 2 = 800 m

(c) (i) Pendulum B and D execute forced vibrations

(ii) Pendulum C will be in a state of Resonance

(iii) Natural frequency of B does not match with Natural frequency of A

Natural frequency of C matches that of A

### Question 8:

(a) (i) Name the device used to increase the voltage at a generating station.

(ii) At what frequency is A.C supplied to residential houses?

(iii) Name the wire in a household electrical circuit to which the switch is connected.

(b) The relationship between the potential difference and the current in a conductor is stated in the form of a law.

(i) Name the law.

(ii) What does the slope of V- I graph for a conductor represent?

(iii) Name the material used for making the connecting wire.

(c) A cell of Emf 2V and internal resistance 1.2 Ω is connected with an ammeter of resistance 0.8 Ω and two resistors of 4.5 Ω and 9 Ω as shown in the diagram below: (i) What would be the reading on the Ammeter?

(ii) What is the potential difference across the terminals of the cell?

(a) (i) Step up transformer

(ii) 50 hertz

(iii) Live wire.

(b) (i) Ohm’s Law.

(ii) Resistance of the conductor.

(iii) Copper / Aluminium

(c) (i) 1 / R = 1 / R1 + 1 / R2

= 1 / 9 + 1 / 4.5

= 1 / 3

R = 3 Ω

i = E / R + r

= 2 / ( 3 + 1.2 + 0.8 )

= 0.4 A

(ii) V = E – ir

= 2 – 0.4 X 1.2

= 1.52 V

Or V = iR

= 0.4 x ( 3 + 0.8)

= 1.52 V

### Question 9:

(a) (i) Name a gas caused by the Greenhouse effect.

(ii) Which property of water makes it an effective coolant?

(b) (i) Water in lakes and ponds do not freeze at once in cold countries. Give a reason in support of your answer.

(ii) What is the principle of Calorimetry?

(iii) Name the law on which this principle is based.

(iv) State the effect of an increase of impurities on the melting point of ice.

(c) A refrigerator converts 100 g of water at 20⁰ C to ice at -10⁰ C in 35 minutes.

Calculate the average rate of heat extraction in terms of watts.

Given: Specific heat capacity of ice = 2.1 J g-1 ⁰ C-1

Specific heat capacity of water = 4.2 J g -1 ⁰ C-1

Specific Latent heat of fusion of ice = 336 J g-1

(a) (i) CO2 , Water vapours, methane and chloroflouro carbons.( Any one)

(ii) Water has high specific heat capacity/ Specific heat capacity of water is 4200J kg-1 K-1 or any correct value in correct unit

(b) (i) This is because the specific latent heat of fusion of ice is sufficiently high

(336 J/ g), so to freeze water, a large quantity of heat has to be withdrawn, hence it freezes slowly.

(ii) If the system is fully insulated then

Heat energy lost by the Hot body = Heat energy gained by the Cold body.

(iii) Law of conservation of energy.

(iv) Increase of impurity decreases the m.pt. of ice.

(c) m c θ + m L + m c θ = P X t

100 X 4.2 X 20 + 100 X 336 + 100 X 2.1 X 10 = P X 35 X 60

44100 = P X 2100

P = 21 W

### Question 10:

(a) (i) What is thermionic emission?

(ii) Name the unit in which the work function of a metal is expressed. (b) (i) Complete the diagram as given above by drawing the deflection of radioactive radiations in an electric field.

(ii) State any two precautions to be taken while handling radioactive substances.

(c) An atomic nucleus A is composed of 84 protons and 128 neutrons.

(i) The nucleus A emits an alpha particle and is transformed into nucleus B. What is the composition of nucleus B?

(ii) The nucleus B emits a beta particle and is transformed into a nucleus C.

What is the composition of nucleus C?

(iii) Does the composition of nucleus C change if it emits gamma radiations?

(a) (i) Emission of free electrons from a metal surface when heat energy is imparted to it is called the thermionic emission.

(ii) Electron Volt.

(b) (i) Deflection of Alpha and Beta shown correctly, Alpha deflection is less than beta Path of Gamma.