no idea

BITSAT 2015 Sample Questions › Mechanics questions › no idea

Q1 if v' is frequncy of photon which escapes to âˆž from a star and v is its freuncy when it is emmited from surface of star of radius R then v/v'= ?

Q2Gravitational red shift of phototn escaped to âˆž from starts surface is ?

Q3 For a black hole ,calculate range of GM/c²R

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2 Answers

govind ·2010-03-24 13:41:05

The Doppler shift
can be expressed as:
Î”Î½ vradial
----- = â€“--------
Î½ c

The formula given above is valid only when the speed of the source is
small compared to that of light. A more accurate formula for the Doppler
effect which is valid even when the speeds are close to that of light, requires the use of Einsteinâ€™s special theory of relativity. The Doppler effect for light is very important in astronomy. It is the basis for the measurements of the radial velocities of distant galaxies.

So i dont think any such question will be asked..as the Doppler equation that is given abv is only valid wen the speed of the particle << speed of light...but photons travel at the speed of light..