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Write down the uses of Doppler? S Effect

Applications of Doppler Effect

Now we discuss some critical applications of Doppler.’ s effect. –

(j) Radar System

RADAR is an acronym. utäs derived from ‘Radio Detection And Ranging. Radar is a device with: transmits an&receives radio. Waves. ‘The radar system uses to determine the height and speed of the airplane. This system emits radio waves which are reflected from the airplane and received by the system. If •reflecte& waves have shorter wavelengths, then the airplane is moving towards a radar system. If reflected waves have longer wavelengths, then the object is moving away from the radar system. Plane approaching of Fig. A ceding A frequency Shift is used in radar to detect the motion of an airplane

(ii) Speed of Satellite

The speed of satellite can also be determined by sending electromagnetic radiations from Earth. When these are’•reflected after colliding With the satellite, then these are received on the earth. •The value Of Doppler’s shift in the wavelength of these radiations gives the estimation of the speed of the satellite.

(iii) Sonar (Sound Navigation and Ranging)

Sonar is a technique for detecting the presence of objects underwater by an acoustic echo. This system uses ultrasonic waves because they can travel long distances in water. Doppler detection depends on the speed of the target and the detector. The apparent change in frequency is observed, which is 333 Doppler’s shift. In this way, we can locate and detect antisubmarine, etc. Also,

Write down the uses of Doppler

(iv) Speed of Star

By comparing the line spectrum of. Light is coming from a distant star and the light emitted from laboratory source, DoØpler’s I shift can. Be measured to calculate the speed of star concerning Earth. Stars are moving towards them. Earth show blueShift and •away from source show redshift:


The frequency of light emitted by the star increases. (i.e., wavelength decreases) If it• is moving towards the earth, as• compared tff•the light •emitted by stationary star: Thus spectrum is. shiftédi tOwards shorter wavelength, i.e. to the Blüe end Of Spectrum, ‘which is called Blueshift.

Red Shift

The frequency of emitted by the.Star decreases (i..e. wavelength increases) if it is moving away .from earth. Thus spectrum is shifted towardS the longer wavelénglh, i.e. töwards•the Red end of the spectrum, which is called redshift:


Echolocation allows dolphins to detect >rnall differences in the shape. Size and thickness of objects. EXPLANATION dolphins emit ultrasound t, valves in the Corm or echoes which spread . in water. By reflected. Ultrasound Slaves from the obstacles. Dolphin can•decide the location’, shape and size Of the obstacles: •Thé ‘ ultrasonics are emitted. At frequencies or about 50000 c/s. As astronomers have also discovered that all the distant galaxies are moving away from us and by measuring their redshifts; they have•estimated their speed.

(v) Speed of Car

Microwaves are emitted from •a source in the form of short bursts. Each burst is reflected by any moving car,- in a théir way. The reflected bursts •are detected in •the.detectbr. If thesé ace reflected by moving Car, then Doppler’s shift •is observed. By which speed of the car. Is calculated. Microwaves are used to calculate the rate of the vehicle by a computer program.

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