1) ?Choose from the following the statement(s) that is/are true (i) Two permanen

Question

1)

?Choose from the following the statement(s) that is/are true

(i) Two permanent magnets always attract each other.
(ii) If a magnet attracts an object, it is certain that the object is a permanent magnet.
(iii) If a magnet repels an object, it is certain that the object is a permanent magnet.
(iv) A magnetic material can be made into a permanent magnet.

(iii) and (iv) only

2)

he amount of linear expansion of a metal DOES NOT depend on

the specific heat capacity of the rod

3)

A 40-W light bulb emits spherical electromagnetic waves uniformly in all directions. If 45% of the power input to the bulb is emitted as electromagnetic radiation, what is the radiation intensity at a distance 3.0 m from the bulb?

(i)   ?0.16 W.m-2

(ii) ?0.32 W.m-2

(iii)   ?0.35 W.m-2

(iv)   2.1 W.m-2

(iv) only

4)

The current in a wire varies with time according to the relation I = 4 + 3t2 where I is in amperes and t is in seconds. The number of coulombs of charge that pass a cross section of the wire between t = 3.0 s and t = 5.0 s is:

Explanation / Answer

1) (iii) and (iv) only

2)the specific heat capacity of the rod

3) I = P/A = (0.45*40)/(4*3.14*3^2) = 0.16 W m^-2........(i) only

4) 106 C

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