Observe the graph.



What is the frequency of the wave?

Frequency: It is defined as the rate of vibration constituting a wave or time taken by the number of vibration. That is mathematically it is the reciprocal of the time period of the one complete vibration of the wave.

S.I. unit = hertz

Formula used:

also, we know that speed = wavelength × frequency

⇒ wavelength = 4 m {from the figure, because one complete cycle = wavelength, as shown below:)