The phase difference between two points seperated by 0.8 m in a wave of frequency 120 Hz is 0.5 π. The wave velocity is

Options

(a) 144 m/s
(b) 256 m/s
(c) 384 m/s
(d) 720 m/s

Correct Answer:

384 m/s

Explanation:

Phase difference = 2π/λ × Path difference
0.5π = 2π/λ × 0.8 m or λ = (2π × 0.8 m) / 0.5π = 3.2 m
Velocity v = frequency (ʋ) × Wavelength (λ)
= 120 Hz × 3.2 m = 384 m/s.