Question

find the time period if the number of waves are 20 khz​

Answer 1

Answer:

Firstly in you question there should be frequency instead of number of waves.

Anyway

Time period = 1/ frequency

20kh=20000hz

T=1/20000 sec

Answer 2

Answer:

v=1/t

t=1/v

t=1/20000

t=0.0005seconde