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Section A [2*5*4=40] Question 1 (a) State where acceleration due to gravity will be loweri. At an altitude 1200 km from Earth s surface or on Earth s surface ii. On Earth s surface or at a depth of 8 km from Earth s surface (b) i. Why are lorries provided with a steering wheel of diameter larger than that of cars? ii. Name the type of equilibrium in the case of an aeroplane moving at a constant height. (c) i. The work done by Jupiter in revolving the moon is zero though it follows an elliptical and not circular orbit. Justify. ii. State the energy conversion when water flows from a height of 34 m onto a turbine. (d) Give the characteristics of a good source of energy. (e) i. A staircase can be said to be a simple machine. Justify. ii. State two ways by which efficiency of a block and tackle system can be increased. Question 2 (a) The sound of a train s horn is heard much louder at night than at daytime in a silent atmosphere. Give two reasons. (b) i. A ray of light incident at the first surface of a glass prism suffers ___ and ___. ii. The type of glass which produces greater deviation of light rays is ___ (crown/flint). (c) An electromagnetic wave has a wavelength of 100 pm. i. Name the part of spectrum to which it belongs. ii. State one use of the wave. (d) You are provided with four resistances-1 , 2 , 3 and 6 . How will you connect them to obtain an effective resistance of 3 ? Also draw a diagram. (e) Why does a concave lens always form a diminshed image? State two other characteristics of an image formed by it. Question 3 (a) i. Why are cylindrical magnets used in electric generators? ii. State two ways of increasing the magnitude of e.m.f induced in secondary coil of a transformer. (b) Which material is used as a core in- (i) Electric bell (ii) Direct current generator? Give reasons for its use in the respective devices. (c) State the salient features of ring topology of household wiring. (d) i. How does temperature of electrolyte affect its terminal voltage? ii. How does temperature of a substance affect its refractive index? (e) State the objective property ofi. Sound related to its pitch ii. Light related to its colour Question 4 (a) State two ways of increasing rate of thermionic emission in a cathode ray tube.
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