0Anirban Sir wishes you good luck!
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Physics (Science Paper – I) F.M. 80
Time: 2 hours
SECTION A (Attempt all questions)
1(a) i) Where is the centre of gravity of a uniform ring situated?
(ii) ‘The position of the centre of gravity of a body remains unchanged even when the body is deformed.’ State whether the statement is true or false. [1+1]
(b) State the energy changes in the following devices while in use
(i) A loud speaker (ii) A glowing electric bulb [2]
(c) Write an expression to show the relationship between mechanical advantage, velocity ratio and efficiency for a simple machine. [1]
(d) In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain. [2]
(e) During sunset and sunrise, the sun is seen when it is slightly below the horizon. Give reason. [3]
2(a) Does the depth of a tank of water appear to change or remain the same when viewed normally from above? [1]
(b) How will you decide whether a given piece of glass is a concave lens, convex lens or a plane glass plate? [3]
(c) Distinguish between real and virtual images. [3]
(d) What is understood by the term dispersion of light? What is its cause? [2]
(e) Name the unit used for measuring the sound level. [1]
3(a) Name any two electromagnetic waves which have a frequency higher than that of violet light. State one use of each. [2+2]
(b) Can sound waves travel in vacuum? Give reasons. [1+1]
(c) What is non-ohmic resistor? How is its V-I graph? [1+1]
(d) A cell of e.m.f. E and internal resistance r is used to send current I in an external resistance R. Write expressions for (i) the terminal voltage V of the cell, and (ii) the voltage drop across the internal resistance. How are E and V related? [2]
4(a) Describe briefly one way of producing an induced current in a coil. State one factor that determines the magnitude of induced e.m.f. [2]
(b) What are isotopes? Give examples. [2]
(c) State three factors on which rate of emission of electrons from a metal surface depend. [3]
(d) How is the heat capacity of a body related to the specific heat capacity of its substance? [1]
(e) Write two advantages of high specific heat capacity of water. [2]
SECTION B (Attempt any 4 questions)
5(a) A coolie, with a load of 30 kg on his head, walks on the platform. If he walks a distance of 60 m, what is the work done by him? [g=10ms-2] [1]
(b) A force is applied on (i) a non-rigid body and (ii) a rigid body. How does the effect of the force differ in the above two cases? [2+1]
(c) State two factors on which moment of force about a point depends. [2]
(d) Which type of levers have mechanical advantage always less than 1? Give reasons. [2]
(e) State the class of levers and the relative positions of load (L), effort (E) and fulcrum (F) in each of the following cases.
