Question

A string is clamped at both the ends and it is vibrating in its 4th harmonic. The equation of the stationary wave is $Y=0.3\sin \left(0.157x\right)\cos \left(200\pi t\right)$. The length of the string is: (All quantities are in SI units)

• A. $20m$
• B. $80m$
• C. $60m$
• D. $40m$

Answer 1

The correct option is B $80m$

$4\frac{\lambda }{2}=l$
$2\lambda =l$
From equation $\frac{2\pi }{\lambda }=0.157$
$\lambda =40;l=2\lambda =80m$