Question

a source produces 20 crests and 20 troughs in 0.4 sec. Find the frequency of the wave.

Answer 1

since 20 crests are produced in 0.4 sec so 1 crest would b produved in 0.4/20 sec =0.02 sec
this time period. so frequency is 1/T = 1/0.02 =50

Answer 2

The frequency of the wave is 50 Hz

• Frequency is the number of oscillations per second.
• It is given by

                         f = 1/t

• Unit of frequency is 1/s or hertz.
• Now, a wave comprises of a crest and a trough.
• In this problem, we need to find the number of waves produced in 1 s in order to find out the frequency.
• From the given question,

                 20 waves --------- 0.4 s

                   n waves ---------    1 s

                   20 x 1 = n x 0.4

                    n = 20/0.4

                       = 5/0.1

                       = 50 Hz