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. increase by a factor 20
C. increase by a factor 10
D. decrease by a factor 20

Answer

C

Explanation

Here, `v_("air")=350m//s,v_("brass")=3500m//s`
When a sound wave travels from one medium to another medium its frequency remains the same.
`because` Frequency, `upsilon=(v)/(lambda)`
Since `upsilon` remains the same in both the medium
`implies (v_("air"))/(lambda_("air"))=(v_("brass"))/(lambda_("brass"))`
`lambda_("brass")=lambda_("air")xx(v_("brass"))/(v_("air"))=lambda_("air")xx(3500)/(350)=10lambda_("air")`