Question

A plane progressive wave is given by $y=25\cos (2\pi t-\pi x)$ Then the amplitude and frequency are respectively

• A. 25, 100
• B. 25, 1
• C. 25, 2
• D. 50 $\pi ,$ 2

Answer 1

Answer: (B)

Given equation is
$y=25\cos (2\pi t-\pi x)$ ... (1)
Standard equation is
$y=A\cos (\omega t-kx)$ ... (2)
Comparing (1) and (2),
Amplitude, $A=25,\omega =2\pi ,k=\pi$
$\therefore$ Frequency, $n=\frac{\omega }{2\pi }$
$=\frac{2\pi }{2\pi }=1Hz$