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

Answer

C

Explanation

Frequency of wave must be same in both the cases
`upsilon_(a) = lambda_(a) v`
`upsilon_(b) = lambda_(b) v`
`(upsilon_(a))/(upsilon_(b)) = (lambda_(a))/(lambda_(b))`
`(lambda_(b))/(lambda_(a)) = (upsilon_(b))/(upsilon_(a)) = (3500)/(350) = 10`
`lambda_(b) = 10 lambda_(a)`