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

Question

The phase difference between two points separated by 0.8 m in a wave of frequency 120 Hz is 0.5 π. The wave velocity is (A) 144 ms -1 (B) 384 ms -1 (C) 256 ms -1 (D) 720 ms -1

Tardigrade Admin · Accepted Answer

Here, n=120 Hz, x=0.8 m , φ=0.5 π From φ=(2 π/λ) x, λ=(2 π x/φ)=(2 π × 0.8/0.5 π)=3.2 m ⇒ v =n λ=120 × 3.2=384 ms -1

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

$144 m s^{- 1}$

$384 m s^{- 1}$

$256 m s^{- 1}$

$720 m s^{- 1}$

Here, $n = 120 Hz$ ,
$x = 0.8 m, ϕ = 0.5 π$
From $ϕ = \frac{2 π}{λ} x,$
$λ = \frac{2 π x}{ϕ} = \frac{2 π \times 0.8}{0.5 π} = 3.2 m$
$\Rightarrow v = nλ = 120 \times 3.2 = 384 m s^{- 1}$

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

144ms−1

384ms−1

256ms−1

720ms−1