A progressive wave of frequency $50 \mathrm{~Hz}$ is travelling with velocity $350 \mathrm{~m} / \mathrm{s}$…

A progressive wave of frequency $50 \mathrm{~Hz}$ is travelling with velocity $350 \mathrm{~m} / \mathrm{s}$ through a medium. The change in phase at a given time interval of $0 \cdot 01 \mathrm{~s}$ is
  1. $\frac{\pi}{2} \mathrm{rad}$
  2. $\pi$ rad
  3. $\frac{\pi}{4}$ rad
  4. $\frac{3 \pi}{2} r a d$

Solution

$\lambda=\frac{350}{50}=7 m$ $x=\text { velocity } \times \text { time }=350 \times 0.01=3.5 m$ Phase change $\frac{2 \pi x}{\lambda}=\frac{2 \pi}{7} \times 3.5=\pi$ radian

Asked in: MHT CET 2020 (14 Oct Shift 1)

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