Explain Doppler Effect Of light?? Based on ncert class 12 wave optics
Answers
Answer:
Doppler Effect is the shift in frequency of light when there is relative motion between the source and observer.
It is used to measure the speed of a receding object.
When the source is moving away from the observer then the wavefronts have to travel a greater distance to reach the observer.
When a star is moving away from the earth the wavelength in the middle of the visible region of the spectrum moves towards the red end of the spectrum.
As a result star looks more reddish when moves away from the earth.
This is known as red shift phenomenon.
When the waves are received from a sourcemoving towards the observer, there is an apparent decrease in wavelength. This is called blue shift.
The fractional change in frequency (Δν/ν)=(–vradial/c),
Where vradial= component of the source velocity along the line joining the
observer to the source; vradial is considered positive when the source moves away from the observer.
Thus, the Doppler shift can be expressed as:
(Δν/ν) = (–vradial/c);
It is valid when the speed of the source is small compared to that of light.