Question

explain Doppler effect in light. Distinguish between red shift and blue shift

Answer 1

The doppler effect is the change in frequency or wavelength of a wave for an observer who is moving relative to the wave source . It was named after Austrian Physicist Christian Doppler in 1842 .


BLUESHIFT : A blueshift is any decrease in wavelength, with a corresponding increase in frequency, of an electromagnetic wave; the opposite effect is referred to as redshift.

In visible light, this shifts the color from the red end of the spectrum to the blue end.

Answer 2

Answer:

Doppler's effect in light:-

To an observer on the earth the light from a star moving towards him appears with high frequency or less wavelength. Similarly, the apparent wavelength is high in the case of star moving away from him. This change in apparent frequency or wavelength of light due to relative motion of the source is called Doppler effect.

The Doppler shift is given by

delta(v) by v=-Vradical/c

where Vradical is component of source velocity along the line joining the observer and the source and c is velocity of light.

Vradical is positive when source is moving away from the observer.

The Red shift:-

When a light source is moving away from an observer with a velocity 'v' then frequency observed by the observer is less than the frequency emitted by the source (or) the apparent wavelength increases ie. shift towards the red end of the spectrum.

The Blue shift:-

when a light source is approaching an observer with a relative velocity 'v' then the apparent frequency observed by the observer is more than the frequency emitted by the source (or) the apparent wavelength decreases ie.., shift towards the blue end of the spectrum.