IIT JEE Physics Final Revision Set 44

1. A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth.
(A) The acceleration of S is always directed towards the centre of the earth.
(B) The angular momentum of S about the centre of the earth changes in direction, but its magnitude remain constant
(C) the total mechanical energy of S varies periodically with time
(D) The linear momentum of S remains constant in magnitude


2. The torque r on a body about a given point is found to be equal to A × L where A is a constant vector and L is the angular momentum of the body about that point. From this it follows that:
(A) (dL)/dt is perpendicular to L at all instants of time.
(B) the component of L in the direction of A does not change with time.
(C) the magnitude of L does not change with time.
(D) L does not change with time.

3. In a p-n junction diode not connected to any circuit :
(A) the potential is the same everywhere
(B) the p-type side is at a higher potential than the n-type side
(C) there is an electric field at the junction directed from the n-side to the p-type side.
(D) there is an electric field at the junction directed from the p-type side to the n-type side.


4. During the melting of a slab of ice at 273K at atmospheric pressure :
(A) positive work is done by the ice-water system on the atmosphere.
(B) positive work is done on the ice-water system by the atmosphere.
(C) the internal energy of the ice-water system increases.
(D) the internal energy of the ice-water system decreases.

5. A spherical surface of radius of curvature R, separates air) refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O and PO = OQ. The distance PO is equal to :
(A) 5R (B) 3R
(C) 2R (D) 1.5R

Source: 1998 JEE