A body vibrating with a certain frequency sends waves of wavelength 15 cm in a medium A and 20 cm in medium B. If `vv` of waves in A is `120 ms^-1`. That in B will be

Options

A. `196ms^-1`
B. `160ms^-1`
C. `360ms^-1`
D. `260ms^-1`

Answer

B

Explanation

When a wave moves from one medium to another its frequency doesn't change.
`f=V/(lambda)`
`V_A/V_B=lamda_A/(lambda_B)`
`V_A=120ms^-1,lambda_A=15 cm ,lambda_B=20cm,V_B=?`
`implies120/V_B=15/20`
`V_B=(20xx120)/15=160ms^-1`