Q. 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 $0.2\ m$
Explanation
(b) Phase difference between two successive crest is $2\pi.$
Also, phase difference $(\mathrm{\Delta}\phi) = \frac{2\pi}{T}$ time interval $(\Delta t)$
$\Rightarrow 2\pi = \frac{2\pi}{T} \times 0.2 \Rightarrow \frac{1}{T} = 5\sec^{- 1} \Rightarrow n = 5\ Hz$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.