Question

A car makes sound as it moves toward a stationary observer. What best describes the sound wave heard by the observer compared with the sound heard by the car’s driver?

higher frequency; shorter wavelength
higher frequency; longer wavelength
lower frequency; shorter wavelength
lower frequency; longer wavelength

Answer 1

The frequency will be higher, meaning the wavelength will be shorter.

Answer 2

higher frequency; shorter wavelength

Step-by-step explanation:

As we know that by Doppler's effect of sound we have a formula of apparent frequency observed by stationary observer when source is coming closer to it is given by

`f_(app) = f_o((v)/(v- v_s))`

now when source will come closer to stationary observer than the apparent frequency observed by the observer will be greater than the actual frequency heard by the driver

now we also know that the formula for wavelength is given by

`\lambda = (speed)/(frequency)`

so here the wavelength will be smaller by that observer as frequency will be more.

so correct answer will be

higher frequency; shorter wavelength