Question

Define Doppler effect? and their applications? ​

Answer 1

Answer:

Definition: Doppler Effect refers to thechange in wave frequency during therelative motion between a wave source and its observer. Edwin Hubble madethe discovery that the universe expands as a consequence of the Doppler Effect. It has important applications in the fields of astronomy and space technology.

Doppler Effect (Sound) and its Application

Introduction

In physics, the Doppler Effect can be defined as, “The increase or decrease in the frequency of sound and also to other waves such as the source and observer moving toward or away from each other. Thus the effect causes the change in pitch which is clearly noticed in a passing siren or train horn, as well as in the red shift/blue shift.

The Doppler Effect is familiar to us with everyday experiences. It explains us the change in the pitch of a fast moving car horn or any other fast moving sound source as it passes us. If the car is approaching us, the pitch of the car’s horn will be greater than if the car were stationary and as the car passes us and begins to move away from us the pitch will be lower than if the car were stationary. In fact, whenever the source and observer of a sound are in relative motion, the observed frequency will be different than that of the emitted one by the source.

For example:

The Observer feel higher frequency, when the train is coming to the observer.

The Observer feel lower frequency, when the train is going far from the observer.

History:

The Doppler Effect was discovered by a scientist named Christian Doppler, who gifted his idea to us in year1842. He thought, “if sound wave coming from the source might have a greater frequency and if the source is moving toward or the observer so there will be lower frequency if the source is moving away from the observer. Though some doubted the existence of this phenomenon, it was experimentally verified in 1845 by C. H. D. Buys Ballot (1817-1890) of Holland. Buys Ballot examined the alteration in pitch as he was passed by a locomotive carrying several trumpeters, all playing a constant note. The Doppler effect is considered most often in relation to sound (acoustic waves) and light (electromagnetic waves) but holds for any wave. When the source and observer of light waves move apart, the observed light will be shifted to lower frequencies, towards the “red” end of the spectrum, while if the source and observer move toward each other the light will be shifted to higher frequencies, towards the “blue” end of the spectrum.

Answer 2

The Doppler effect is a change in the pitch of a sound that occurs when the source of the sound is moving relative to the listener.

For example, besides police radar, the Doppler effect is used by meteorologists to track storms.

The Doppler effect is used to measure the velocity detected objects where a radar beam is fired at a moving target.

Applications of Doppler effect-

1. Use in Flow Measurement
2. Use in Vibrant Measurement
3. Use in Audio
4. Use in Velocity profile measurement
5. Use in Medicals

Hope it helps you.