MCQ
The phase difference between two points separated by $1m$ in a wave of frequency $120 Hz$ is ${90^o}$. The wave velocity is .... $m/s$
- A$180$
- B$240$
- ✓$480$
- D$720$
✓
Answer
Correct option: C.
$480$
c
(c) Path difference $\Delta = \frac{\lambda }{{2\pi }} \times \phi $
(c) Path difference $\Delta = \frac{\lambda }{{2\pi }} \times \phi $
==> $1 = \frac{\lambda }{{2\pi }} \times \frac{\pi }{2}$
==> $\lambda = 4m$
Hence $v = n\lambda = 120 \times 4 = 480\,m/s$
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