KVPY 2019 SB SX Exam Previous Papers

Question : 31 of 120

Marks: +1, -0

A photon falls through a height of 1 km through the earth's gravitational field. To calculate the change in its frequency, take its mass to be

{ hv}/c^2

. The fractional change in frequency v is close to

Solution:

hv' = hv + mgh

m={hv}/c^2

⇒

{v'-v}/v={gh}/c^2=1.12 × 10^{–13}

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