Question

For a longitudinal wave; there is a lot of maximum compression at a point at an instant. The frequency of the Wave is 50 Hz. After what time will the same point be in state of maximum rarefaction.?

Answer 1

T=1/freq.
T=1/50
T=0.02s
the time period is 0.02s
but we are talking about the next rarefaction not compression so, T/2 = 0.01 s

Answer 2

frequency f = 50 Hz
 Time period = 20 ms = 0.02 s

Same point will be in maximum rarefaction after a half-time period.
So after 0.01 sec.