The Doppler Effect
You're sitting in a jam. Airport Road Jam. An ambulance is rushing along the road opposite to you, honking its siren! You are praying in your heart that whoever is inside the ambulance, he should reach the hospital as soon as possible. 🙁 But the closer the ambulance gets to you, the more annoying the siren sounds! When the ambulance was passing by you, it seemed that it was over! This discomfort started to subside after you passed, then it didn't happen again later. Why is that? What is it for? Today's discussion of the Doppler effect in physics is to answer these questions.
The Doppler effect is the change in the frequency of a wave due to the relative motion between the source and the observer. The definition seems a little difficult, doesn't it? Let's do a detailed research on it, then you will see that it is straight like water. To better understand this, let us recall the incident I mentioned earlier when the sound of the siren was getting louder as the ambulance was advancing on the siren.
The fact that the ambulance was coming to you with a siren sounded, but not that the louder or louder the sound came out of the speaker as it approached you! But they remain unchanged! But still you can hear loud and sharp sounds only because of the increase in its apparent frequency. 🙂 And due to the relative velocity of the listener (you) and the source (siren mounted above the ambulance) the apparent change in the frequency of the sound wave is felt, this is the Doppler effect! This Doppler effect is seen only in the case of words but not! We look at how matter works in the case of just sound waves.This applies to any wave.
A few important things:
1) The Doppler effect will be felt in the direction where the apparent velocity of the listener or source exists. An ambulance is heading east with a siren sounding, you stand on the ambulance and jump. The direction of your jump must be along the north here. Since the angle difference between the source and the listener's velocity is 90 degrees, the Doppler effect will not work here.
2) Doppler effect will not work if the speed of sound from the source is less than the speed of the listener.