Question

A body sends waves 100 mm long through medium P and 0.25 m long in medium Q. If the velocity of the wave in medium P is 80 cms^-1. The velocity of the wave in medium Q is ______.

Options

• 1 ms^-1

• 2 ms^-1

• 5 ms^-1

• 7 ms^-1

Answer 1

A body sends waves 100 mm long through medium P and 0.25 m long in medium Q. If the velocity of the wave in medium P is 80 cms^-1. The velocity of the wave in medium Q is 2 ms^-1.

Explanation:

Given, λ_P = 100 mm = 0.10 m

λ_Q = 0.25 m

v_P = 80 cms^-1 = 0.80 ms^-1

Since the frequency of wave remains the same in the two media,

`"v"_"P"/lambda_"P" = "v"_"Q"/lambda_"Q"` `(∵ ν = "v"/lambda)`

⇒ v_Q = `lambda_"Q"/lambda_"P" xx "v"_"P" = 0.25/0.10 xx 0.80 = 2` ms^-1