Question
The phase difference between two points separated by $0.8 m$ in a wave of frequency is $120 Hz$ is $\frac{\pi }{2}.$ The velocity of wave is ..... $m/s$
✓
Answer
b
(b) Phase difference $ = \frac{{2\pi }}{\lambda } \times$ path difference
(b) Phase difference $ = \frac{{2\pi }}{\lambda } \times$ path difference
$ \Rightarrow \frac{\pi }{2} = \frac{{2\pi }}{\lambda } \times 0.8$
$ \Rightarrow \lambda = 4 \times 0.8 = 3.2\,m$
Velocity $v = n\lambda $$ = 120 \times 3.2 = 384\,m/s.$
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