Two starts `P` and `Q` have slightly different surface temperature `T_(P)` and `T_(Q)` respectively, with `T_(P)gtT_(Q)`. Both starts are receding from the earth with speeds `v_(P)` and `v_(Q)` relative to the earth. The wavelength of light at which they radiate the maximum energy is found to be the same for both.

Options

A. `v_(p) gt v_(Q)`
B. `v_(p) lt v_(Q)`
C. `v_(P) = v_(Q)` and the size of Q gt the size of P
D. Nothing can be said regarding `v_(P)` and `v_(Q)` from the given data

Answer

A

Explanation

As `T_(p) lt T_(Q)` wavelength of maximum energy by Q will be more than that ofP and as on earth both wavelengths received are same hence P is receding with more speed as the received wavelength by the observer behind a moving source will increase with the speed.