Sounds waves travel at `350m//s` through a warm air and at `3500m//s` through brass. The wavelength of a `700 Hz`. Acoustic wave as it enters brass from warm air

Options

A. increases by a factor 20
B. increases by a factor 10
C. decreases by factor 20
D. decreases by a factor 10

Answer

B

Explanation

Velocity of sound `v=nlamda`
`(v_1)/(v_2)=(n_1lamda_1)/(n_2lamda_2)` (but `n_1=n_2`)
`lamda_2=lamda_1(v_2)/(v_1)=lamda_1xx10`
`lamda_2=10lamda_1`