Question

The equation of a stationary wave is given by $y=6\sin \left(\frac{\pi x}{3}\right)\cos 40\pi t$ where $y$ and $x$ are given in $cm$ and time $t$ in second, then the amplitude of progressive wave is:

• A. $3cm$
• B. $2cm$
• C. $6cm$
• D. $12cm$

Answer 1

The correct option is A $3cm$

Given,
$y=6\sin \left(\frac{\pi x}{3}\right)\cos 40\pi t$
Comparing it with the standard form
i.e.
$y=2A\sin kx\cos \omega t$
$2A=6orA=3cm$

Final answer: (b)