Waves Ques 31
31. Equation of a progressive wave is given by $y=4 \sin [\pi(\frac{t}{5}-\frac{x}{9})+\frac{\pi}{6}]$ Then which of the following is correct?
[1988]
(a) $v=5 $ $cm$
(b) $\lambda=18 $ $cm$
(c) $a=0.04 $ $cm$
(d) $f=50 $ $Hz$
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Answer:
Correct Answer: 31.(b)
Solution:
- (b) The standard equation of a progressive wave is
$y=a \sin [2 \pi(\frac{t}{T}-\frac{x}{\lambda})+\phi]$
The given equation can be written as
$y=4 \sin [2 \pi(\frac{t}{10}-\frac{x}{18})+\frac{\pi}{6}]$
$\therefore a=4 cm, T=10 s, \lambda=18 $ $cm$ and $\phi=\pi / 6$
Hence, (b) is correct.
BETA
