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GOLDCREST HIGH, LATUR On the Wings Of Excellence PRACTICE PAPER FOR THE ICSE (2018-19) PHYSICS (Two hours) Answer 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 this paper is the time allowed for writing the answers. Attempt all the questions from Section I and any four questions from Section II. The intended marks for the questions or parts of the questions are given in brackets []. Section-I (Attempt ALL questions) Question. 1 a. What is the weight of the body placed at the centre of the Earth? b. Name the factors affecting turning effect of a body. c. Define energy and state its SI units. d. What should be the angle between the force and the displacement to get the: (i) Minimum work? (ii) Maximum work? e. State the energy changes in the following while in use: (i) Burning of a candle. (ii) A steam engine. f. What is the SI unit of moment of force? [1] [2] [2] [2] [2] [1] Question. 2 a. A uniform meter rule balances horizontally on a knife edge at 29 cm mark when a weight of 20 gf is suspended from one end. (i) Draw a diagram of the arrangement. (ii) What is the weight of the meter rule? [2] b. State the class of levers and the relative positions of the load (L), fulcrum (F) and effort (E) in each of the following cases: (i) A bottle opener. (ii) Sugar tongs. [2] c. State the dependence of angle of deviation of light while passing through the prism: (i) On the refractive index of the material of the prism. (ii) On the wavelength of the light. [2] d. A postage stamp kept below a rectangular glass slab of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass slab. [2] e. We can burn a piece of paper by focusing the sun rays by using a particular type of lens. (i) Name the type of the lens used for the above purpose. (ii) Draw a ray diagram to support your answer. [2] Page 1 of 5 Question. 3 a. Explain why musical instruments like the guitar are provided with a hollow box? [2] b. A bucket kept under running tap is getting filled with water. A person sitting at a distance is able to get an idea when the bucket is about to be filled. (i) What change takes place in the sound to give this idea? (ii) What causes the change in the sound? [2] c. Four resistances of 2.0 each are joined end to end, to form a square ABCD. Calculate the equivalent resistance of the combination between any two adjacent corners. [2] d. What happens to the resistivity of a semi conductors with the increase of temperature? [2] e. How does the heat produced in a wire or a conductor depend upon the: (i) The current passing through the conductor? (ii) Resistance of the conductor? [2] Question. 4 a. When does the nucleus of an atom tend to be radioactive? b. Define Isobars. c. State two ways by which the EMF of an AC generator can be increased. d. Why is water used as a universal coolant? e. What do you inderstand by the following statements? (i) The heat capacity of a body is 60JK-1. (ii) The specific heat capacity of Lead is 130Jkg-1K-1. [2] [2] [2] [2] [2] Section-II (Attempt any four questions) Question. 5 a. A pulley has a velocity ratio of 4 and an efficiency of 90%, calculate: (i) The mechanical advantage of the system. (ii) The effort required to raise the load of 300 N by the system. [3] -1 b. A bullet of mass 50 g is moving with a velocity of 500 ms . It penetrates 10 cm into a still target and comes to rest. Calculate the: (i) Kinetic energy of the bullet. (ii) The average retarding force offered by the target. [3] c. A spanner (or wrench) has a long handle. Why? [2] d. Define Centripetal force. [2] Page 2 of 5 Question. 6 a. A lens forms an erect, magnified and virtual image of the object. (i) Name the lens. (ii) Draw a labeled ray diagram to show the image formation. b. Complete the ray diagram for the following: (Given Critical angle for glass air media is 42 (i) [3] (ii) [3] c. Name any two electromagnetic waves, which have a frequency higher than that of violet light. State one use of each. [2] d. Why is red colour used as a sign of danger? [2] Question. 7 a. In the diagram given 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 reasons for the type of vibrations in pendulum B and C. [3] b. A man standing in front of a vertical cliff fires a gun. He hears the echo after 3 s. On moving closer to the cliff by 82.5m, he fires again. This time he hears the echo after 2.5 s. Calculate: (i) The distance of the cliff from the initial position of the man. (ii) The velocity of sound. [3] c. A battery of e.m.f 12 V and internal resistance 2 is connected with two resistors A and B of resistance 4 and 6 respectively joined in series. Find: (i) Current in the circuit. (ii) The terminal voltage of the cell. (iii)Electrical energy spent per minute in 4 resistor. [4] Page 3 of 5 Question. 8 a. The equivalent resistance of the following circuit diagram is 4 . Calculate the value of x. [3] b. An electrical appliance is rated 1500 W, 250 V. This appliance is connected to 250 V mains. Calculate: (i) The current drawn. (ii) The electrical energy consumed in 60 hours. (iii)The cost of electrical energy consumed at Rs 2.50 per kWh. [3] c. The diagram shows a coil connected to a galvanometer G. The galvanometer shows a deflection. (i) Explain why does the galvanometer show a deflection. (ii) Does the direction of current in the coil appear clockwise or anticlockwise when viewed from the end A? (iii)State the observation in G when the coil is moved away from N. (iv) State the observation in G when both the coil and the magnet are moved to the right at the same speed. [4] Question. 9 a. A piece of ice is heated at a constant rate. The variation of temperature with heat input is shown in the graph here. [3] (i) What are represented by AB and CD? (ii) What conclusion can you draw regarding the nature of the ice from the graph shown below? b. Water falls from a height of 50 m. Calculate the temperature of water, when it strikes the bottom. (g = 10 ms-2, specific heat capacity of water = 4200 J/kg C) [3] Page 4 of 5 c. An element X changes to another element Y with the emission of particles. Write down the equation showing the changes in the nucleus. Take the proton number and mass number of X as Z and A respectively. [2] A 222 d. An element ZS decays to 85R after emitting 2 particles and 1 particle. Find the atomic number and atomic mass of the element S. [2] Question. 10 a. It is known that 92U238 (Uranium nucleus) decays to finally form the stable lead nucleus 82Pb206. What is the number alpha particles and Beta particles emitted in this decay process? [4] b. Complete the following nuclear changes: [2] 24 ___ 0 (i) 11Na + 1 ___Mg 234 (ii) 92U238 + ___________ + Energy. 90Th c. A mixture of radioactive substances gives off three types of radiations. (i) Name the radiation which travels with the speed of light. (ii) Name the radiation which has the highest ionizing power. [2] d. A certain radioactive nucleus emits a particle that leaves its mass unchanged but increases its atomic number by one. Identify the particle and write its symbol. [2] _______________________________________________________________________________________ Page 5 of 5
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