Question

Explain what is the Doppler effect in sound and state its any four applications.

Answer 1

Hint: The given question can easily be answered if we have a clear understanding of the frequencies of sound and its different effects. This is a conceptual question. So, we need to have a clear concept of the Doppler effect. Then only we can answer the given question properly.

Complete step by step answer:
First of all we need to define the Doppler effect.
We can define the Doppler effect as the relative increase or decrease in the frequency of sound or other waves as the source of frequency and observer move towards or away from each other. Doppler effect is also known as Doppler shift. This phenomenon is generally observed when the source of wave or frequency is moving with respect to an observer. In other words we can say that the Doppler effect is the change in the frequency of the waves as a result of the relative motion between the source of sound and the observer. Mathematically, we can write it as,
${f'} = \dfrac{{(v \pm {v_0})}}{{(v \pm {v_s})}}f$
Where, $f'$= observed frequency
$f$= actual frequency
$v$= velocity of the sound waves
${v_0}$= velocity of the observer
${v_s}$= velocity of the source
Now, let us write down the application of the Doppler effect.
It is used in the measurement of vibration, astronomy, radar system, sirens, satellite communication etc.
Hence, we have defined the Doppler effect with its applications.

Note: We should not consider the Doppler effect to be valid only for sound waves. It is applicable for all types of waves. We can use the Doppler effect only when the velocities of the observer and the source of the sound are less than that of the velocity of sound.