Question

A sound wave is vibrating at frequency 50 Hz. What is its time period ?

Answer 1

The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency.
Here, a sound wave is vibrating at frequency 50 Hz. Hence, the time period T = 1/f = 1/50 = 0.02 s.
Hence, the sound wave vibrating at frequency 50 Hz has a time period of 0.02 s.