Question

A wave source produces 50 crests and 50 troughs in 0.2 seconds. Find the frequency of the wave.

• A.
  $200Hz$
• B.
  $250Hz$
• C.
  $300Hz$
• D.
  $500Hz$

Answer 1

The correct option is B

$250Hz$
One oscillation consists of a crest and a trough.

So, 50 crests and 50 troughs together make 50 oscillations.

Given that the time taken for 50 oscillations is 0.2 seconds.

Since the frequency ($f$) of a wave is the number of oscillations made in one second,

$f=\frac{50}{0.2}=\frac{500}{2}=250$
Frequency $=250Hz$