Solving ICSE Class 10 Physics Previous Year Question Papers ICSE Class 10 Physics Question Paper 2015 is the best way to boost your preparation for the board exams.
ICSE Class 10 Physics Question Paper 2015 Solved
Time : 2 hours
Maximum Marks: 80
General Instructions:
- Answers to this paper must be written on the paper provided separately.
- You will not be allowed to write during the first 15 minutes. This time is to be spent in reading the question paper.
- The time given at the head of paper is the time allotted for writing the answers.
- Attempt all questions from Section I and any four questions from Section II.
- The intended marks of questions or parts of questions are given in brackets [ ].
Section – I
(40 Marks)
Attempt all question from this Section.
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. [2]
Force due to weight of the body
(i) Name the force exerted by the table top.
(ii) What is the direction of the force?
Answer:
(i) Reaction force.
(ii) Upwards.
(b) (i) Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab. [2]
(ii) On reversing the direction of the current in a wire, the magnetic field produced by it gets _________ .
Answer:
(i) Refractive index of glass.
(ii) Reversed.
(c) (i) On what factor does the position of the centre of gravity of a body depend? [2]
(ii) What is the SI unit of the moment of force?
Answer:
(i) Distribution of mass.
(ii) N m.
(d) Name the factors affecting the turning effect of a body. [2]
Answer:
The following are the factors which affect the turning effect of a body:
- Magnitude of force.
- Distance of point of application of force from the axis of rotation.
- Angle between force and distance from axis of rotation.
(e) (i) Define equilibrium. [2]
(ii) In a beam balance when the beam is balanced in a horizontal position, it is in equilibrium.
Answer:
(i) It is a state in which net force acting on a body or system is zero.
(ii) Stable.
Question 2
(a) How is work done by a force measured when the force: [2]
(i) is in the direction of displacement?
(ii) is at an angle to the direction of displacement?
Ans.
(i) W = FS
(ii) W = FS cos θ
(b) State the energy changes in the following while in use: [2]
(i) Burning of a candle.
(ii) A steam engine.
Answer:
(i) Chemical energy into light and heat energy.
(ii) Heat energy into mechanical energy.
(c) (i) A scissor is a multiplier.
(ii) 1 kWh = _______ J. [2]
Answer:
(i) Velocity.
(ii) 3.6 × 106 J
(d) Explain the motion of a planet around the Sun in a circular path. [2]
Answer:
A planet revolves around the sun due to gravitational force between it and the sun. The gravitational force provides the necessary centripetal force for the circular motion.
(e) Rajan exerts a force of 150 N in pulling a cart at a constant speed of 10 m/s. Calculate the power exerted. [2]
Answer:
P = F × v = 150 × 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. [2]
(ii) Name a common device where a gear train is used.
Answer:
(i) M.A. = \(\frac{l}{h}\)
(ii) Watch.
(b) The speed of light in glass is 2 × 105 km/s. What is the refractive index of glass? [2]
Answer:
Refractive index µ = \(\frac{c}{v}=\frac{3 \times 10^8}{2 \times 10^8}\) = 1.5
(c) (i) Draw a graph between displacement and the time for a body executing free vibrations. [2]
(ii) Where can a body execute free vibrations?
Answer:
(i) The graph is as shown :
(ii) In vacuum.
(d) (i) What happens to the resistivity of semi-conductor with the increase of temperature? [2]
(ii) For a fuse, higher the current rating is the fuse wire.
Answer:
(i) It decreases.
(ii) Thicker.
(e) (i) Name the high energetic invisible electromagnetic waves which help in the study of the structure of crystals. [2]
(ii) State an additional use of the waves mentioned in part (i).
Answer:
(i) X-rays.
(ii) Diagnostic tool.
Question 4
(a) Rishi is surprised when he sees water boiling at 115.C in a container. Give reasons as to why water can boil at the above temperature. [2]
Answer:
The boiling point of water depends upon the pressure at which it is boiled. Higher the pressure, higher is the boiling point of water.
(b) (i) Why does a current carrying, freely suspended solenoid rest along a particular direction? [2]
(ii) State the direction in which it rests.
Answer:
(i) This is because when current is passed through the solenoid it begins to act as a magnet.
(ii) It rests in the north-south direction.
(c) Find the equivalent resistance between points A and B. [2]
Answer:
Resistors of 4 Ω,6 Ω and 12 Ω are in parallel, therefore, equivalent resistance of these three
\(\frac{1}{R}=\frac{1}{4}+\frac{1}{6}+\frac{1}{12}=\frac{12}{24}=\frac{1}{2}\) or R = 2 Ω
Now, R is connected in series with 2 Ω. and 5 Ω resistors, hence equivalent resistance of the combination is R Req = 2 + 5 + 2 = 9 Ω
(d) Give two similarities between an AC generator and a DC motor [2]
Answer:
- Both have a concave shaped field magnet.
- Both have an armature.
(e) (i) Why is a cathode ray tube evacuated to a low pressure? [2]
(ii) What happens if the negative potential is changed on a grid?
Answer:
(i) So that the electrons emitted do not collide with the
gas molecules.
(ii) The change in negative potential changes the number of electrons striking the screen which in turn changes the brightness of the screen.
Section – II (40 Marks)
Attempt any four questions from this Section.
Question 5
(a) Draw a simplified diagram of a lemon crusher, indicting direction of load and effort. [2|
Answer:
The diagram is as shown :
(b) (i) Name the physical quantity measured in terms of horse power. [4]
(ii) A nut is opened by a wrench of length 20 cm. 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.
Answer:
(i) Power.
(ii) Moment of force = force × length of arm
= 2 × 0.2
= 0.4 N m.
(iii) When a cricketer catches the ball he applies a force opposite to the direction of motion of the ball. Since the displacement of the ball and the force applied are opposite, therefore, the work done is negative.
(c) A block and tackle system has V.R. = 5. [4]
(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%?
Answer:
(i) The diagram is as shown :
(ii) η = \(\frac{\text { M.A. }}{\text { V.R. }}=\frac{L}{E n}\)
where n is the number of pulleys.
or 0.75 = \(\frac{\mathrm{L}}{150 \times 5}\)
or L= 0.75 × 150 × 5
or L = 562.5 kgf
Question 6
(a) (i) Where should an object 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).
Answer:
(i) At 2F.
(ii) The ray diagram is as shown :
(b) (i) Why does the Sun appear red at sunrise? [3]
(ii) Name the subjective property of light related to its wavelength.
Answer:
(i) Light from the Sun, near the horizon, passes through thicker layers of air and covers a large distance in the earth’s atmosphere before reaching our eyes.
However, light from the Sun overhead would travel relatively shorter distance. At noon, the Sun appears white as only a little of the blue and violet colours are scattered. Near the horizon, most of the blue light and shorter wavelengths are scattered away by the particles. Therefore, the light that reaches our eyes is of longer wavelengths. This gives rise to the reddish appearance to the Sun.
(ii) Colour.
(c) Jatin puts a pencil into a glass container having water and is surprised o see the pencil in a different state. [4]
(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.
Answer:
(i) The pencil seems bent at the water-air interface.
(ii) Refraction of light.
(iii) The ray diagram is as shown :
Question 7
(a) (i) State the safe limit of sound level in terms of decibel for human hearing. [2]
(ii) Name the characteristic of sound in relation to its waveform.
Answer:
(i) 120 dB.
(ii) Timbre.
(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 : [3]
(i) The speed of sound.
(ii) The distance of the other cliff from the person.
Answer:
(i) The first echo is heard from the nearest cliff.
Let d1 be the distance of the nearest cliff. Then distance travelled by sound in going and coming back from the nearest cliff is
S1 = 2d1= 480 × 2 = 960 m
Time interval t1 = 3 s
Therefore, Speed of sound is
v = \(\frac{\text { Total distance of travelled }}{\text { Time taken }}\)
= \(\frac{960}{3}\) = 320 m s-1
(ii) The second echo is heard from the farther cliff. If d2 is the distance from the person, then distance travelled by sound
S2 = 2d2 and time taken t2 = 3 +2 = 5s
Now, v = \(\frac{\mathrm{S}_2}{t_2}\)
⇒ 320 = \(\frac{S_2}{5}\) ms-1
Therefore, S2 = 320 × 5 = 1600 m
(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 in to a mode of vibrations. [5]
(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 pendulum B and C.
Answer:
(i) Force vibrations.
(ii) Pendulum C, after sometime, will start vibrating with the same amplitude as that of pendulum A.
(iii) The type of vibrations in pendulum B and C are called forced vibrations. In case of pendulum C it comes into a state of resonance and vibrates in phase with pendulum A while pendulum B does not.
Question 8.
(a) (i) Name the device used to increase the voltage at a generating station.
(ii) At what frequency is AC supplied to residential houses?
(iii) Name the wire in a household electrical circuit to which the switch is connected. [3]
Answer:
(i) Transformer.
(ii) 50 Hz.
(iii) Live wire.
(b) The relationship between the potential difference and the current in a conductor is stated in the form of a law. [3]
(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.
Answer:
(i) Ohm’s law.
(ii) Resistance
(iii) Copper.
(c) A cell of Emf 2 V and internal resistance 1.2 U is connected with an ammeter of resistance 0.8 U and two resistors of 4.5 U and 9 U as shown in the diagram below: [4]
(i) What would be the reading on the Ammeter?
(ii) What is the potential difference across the terminals of the cell?
Answer:
(i) Here, 4.5 Ω and 9 Ω resistors are in parallel, therefore, equivalent resistance is
\(\frac{1}{R}=\frac{1}{45}+\frac{1}{9}\)
\(\frac{10}{45}+\frac{1}{9}=\frac{10+5}{45}=\frac{15}{45}=\frac{1}{3}\)
or R = 3 ohm
Now, ammeter and the cell are connected in series with this resistance, hence
Total resistance of the circuit is
Rnet = 3 + 0.8 + 1.2 = 5 ohm
Hence, current through the ammeter and its reading is
I = \(\frac{\mathrm{V}}{\mathrm{R}_{\text {net }}}=\frac{2}{5}\) = 0.4 A
(ii) V = E – Ir
= 2 – 0.4 × 1.2
= 2 – 0.48
= 1.52 V
Question 9
(a) (i) Name a gas caused by the Greenhouse effect. [2]
(ii) Which property of water makes it an effective coolant?
Answer:
(i) Carbon dioxide.
(ii) Unusally high specific heat capacity.
(b) (i) Water in lakes and ponds do not freeze at once in cold countries. Give a reason is 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.
Answer:
(i) In the beginning of winter when the atmospheric temperature drops to ft °C, the water in ponds and lakes do not freeze all at once due to the high latent heat of water. Every kilogram of water when frozen releases 333 kJ of heat energy to the atmosphere warming up the atmosphere. It takes more severe winter (large drop in temperature) and hence, more time for water to freeze. So it happens slowly and gradually.
(ii) “Heat lost by the hot body is equal to the heat gained by the cold body”.
(iii) Law of conservation of energy.
(iv) Impurities decrease the melting point of a solid.
(c) A refrigerator converts 100 g of water at 20°C to ice at -10°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. C-1
Specific heat capacity of water = 4.2 J g-1.C-1
Specific latent heat of fusion of ice = 336 J g-1 [4]
Answer:
Given : mass of water = 100 g
Heat extracted to convert 100 g water at 20°C to water at 0°C
= Mass x Specific heat capacity of water × Change in temperature
= 100 × 4.2 × (20 – 0) = 8400 J
Heat extracted to convert 100 g water at 0°C to ice at 0°C
= Mass × Specific heat capacity of water × Rise in temperature
= 100 × 336 = 33600 J
Heat extracted to convert 100 g ice at 0°C to ice at-10°C
= Mass × Specific heat Capacity of ice × Change in temperature
= 100 × 2.1 × (0- (-10)) = 2100 J
Therefore,
Total heat extracted in 35 minutes = 8400 + 33600 + 2100 = 44100 J
Therefore, average rate of heat extraction is
R = \(\frac{44100}{35 \times 60}\)
= 21 J s-1 = 21 watt
Question 10
(a) (i) What is thermionic emission? [2]
(ii) Name the unit in which the work function of a metal is expressed.
Answer:
(i) The emission of electrons from a metal surface on heating is called thermionic emission.
(ii) Electron volt (eV).
(b) (i) Complete the diagram as given below by drawing the deflection of radioactive radiations in an electric filed. [5]
(ii) State any two precautions to be taken while handling radioactive substances.
Answer:
(i) The completed diagram is as shown alongside.
(ii) A person handling radioactive sources should wear protective clothing and special badge (of photographic emulsion) to monitor the extent of exposure to harmful radiation.
The sources should be handled by the forceps provided. The user should wear rubber gloves. Hands should be washed and even a shower taken after each use.
(c) An atomic nucleus A is composed of 84 protons and 128 neutrons. [3]
(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 nucleus C. What is the composition of nucleus C?
(iii) Does the composition of nucleus C change if it emits gamma radiations?
Answer:
(i) The composition of nucleus B is 82 protons and 124 neutrons.
(ii) The composition of nucleus C is 83 protons and 124 neutrons.
(iii) No.