Question

A travelling wave passes a point of observation. At this point, the time interval between successive crests is 0.2 seconds and

• A. The wavelength is 5 m
• B. The frequency is 5 Hz
• C. The velocity of propagation is 5 m/s
• D. The wavelength is 0.2 m

Answer 1

Answer: (B)

The frequency is 5 Hz

Answer 2

Phase difference between two successive crest is 2π. Also, phase difference $(\Delta\varphi)$ = $\frac{2\pi}{T}$ time interval $(\Delta t)$

⇒ $2\pi = \frac{2\pi}{T} \times 0.2 \Rightarrow \frac{1}{T} = 5\sec^{- 1} \Rightarrow n = 5Hz$