(a) What is meant by the 'time-period' of a vibrating object? State its unit.
(b) Define 'frequency' of a vibrating object. Name the unit in which frequency is measured.
(c) A pendulum oscillates 40 times in 4 seconds. Calculate its (i) time-period. and (ii) frequency. Can we hear the sound produced by the oscillations of this pendulum? Give reason for your answer.
Length of a vibrating string is halved. What will happen to its frequency?
If we double the radius of a current carrying coil keeping the current unchanged. what happens to the magnetic field at its centre?