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

Answer

C

Explanation

Here, `v_(air)=350 m s^(-1), v_(brass) = 3500 m s^(-1)`
When a sound wave goes from one medium to another medium, its frequency (`upsilon`)remains the same.
Frequency,`upsilon=("Velocity")/("Wavelength")=v/lamda`
Since `upsilon` remains the same in both the media so
`(v_(air))/(lamda_(air))=(v_(brass))/(lamda_(brass))`
or `lamda_(brass)=lamda_(air)xx(v_(brass))/(v_(air))=lamda_(air)xx3500/350=10lamda_(air)`