A straight conductor of length 0.6 M is moved with a speed of 10 ms$$^{-1}$$ perpendicular to magnetic field of induction 1.2 weber m$$^{-2}$$. The induced e.m.f. across the conductor is

If the electron in a hydrogen atom moves from ground state orbit to 5^th orbit, then the potential energy of the electron

A particle of mass 5kg is executing S.H.M. with an amplitude 0.3 m and time period $$\frac{\pi}{5}$$s. The maximum value of the force acting on the particle is

The weight of a man in a lift moving upwards with an acceleration 'a' is 620 N. When the lift moves downwards with the same acceleration, his weight is found to be 340 N. The real weight of the man is