Answer: The correct answer is 5 Hz.
Explanation:
The expression for the relation between the speed and wavelength is as follows:
\(v=f\lambda\)
Here, v is the speed of the wave, f is the frequency of the wave and \(\lambda\) is the wavelength.
In the given problem, a wave is moving at the rate of 40 cm/s. Its wavelength is 8 cm.
Put v= 40 cm/s and \(\lambda\)= 8 cm.
\(40 =f(8)\)
\(f = 5 Hz\)
Therefore, the correct option is (A).
