1. A planet is revolving around the sun in an elliptical orbit. The mass of planet is m, angular momentum of planet about sun is L, and length of semi major axis is a and eccentricity is e. Time period of revolution of planet is given by 2ma1+e (1) T = L 2ma1-2 (3) T L (2) T = mma1-e L ma1-e (4) T = 3L Mshikah 2. Metallic disc of inner radius R and outer radius 2R is rotating with an angular speed co. What will be the electric potential difference that appears between the inner and outer periphery. The mass of electrons is m and charge is e. 2R IR 3mw R (1) 26 (3) mwR (4) mwR 2e 2mw2R2 3. Two sources of sound emitting sound of nearly equal wavelengths and 2 are fixed at A and B respectively. A listener moves with velocity u on the perpendicular bisector of line joining A and B. Then the number of beats heard by him per second when it is at distance 21 from A and B, is (Speed of sound C) U (1)(c)() (3) (C-3u)() 20 B (2) (20-4) (-) (4) Zero