Question

Explain Doppler Effect in light. Hence explain the red and blue shift. State its two applications.

Answer 1

Doppler effect in light is analogous to the doppler effect in sound and is the change in frequency and wavelength of light caused by the relative motion between the source and the observer.

When a light source is moving towards an observes the wavelength of the light shifts towards the blue end of the spectrum and a blue shift is observed.

When light sources move away from the observer, the wavelength of the light shifts towards the red end of the spectrum and a redshift is observed.

One main application of the Doppler shift in light to we it finds in measuring the rotational speed of stars and galaxies by measuring the velocity at which they are approaching or receding from us.

They are also used in speed guns to measures the speed of fast-moving objects.[