Question

The equation $y=0.02\sin (500\pi t)\cos (4.5x)$ represents

• A. progressive wave of frequency 250 Hz along $x$ -axis
• B. a stationary wave of wavelength 1.4 m
• C. a transverse progressive wave of amplitude 0.02 m
• D. progressive wave of speed of about $350m{s}^{-1}$

Answer 1

Answer: (B)

A stationary wave equation is
$y=A\sin \omega t\cos kx$
Here $k=4.5=\frac{2\pi }{\lambda }$ or
$\lambda =\frac{2\pi }{4.5}=1.4$ units.