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[tex]

\frac{\lambda}{\lambda_o} = 1 - \frac{GM}{r c^2}

[/tex]

From http://scienceworld.wolfram.com/physics/GravitationalRedshift.html

Where [tex] \lambda [/tex] is the shifted wavelength and [tex] \lambda_o [/tex] is the rest wavelength.

r is the distance from the gravitating body with mass M

The photon is being emitted from the surface of M directly away from the centre of M.

As r is increased and M constant, the redshift is increased as I expected. The photon has to climb further which reduces its energy which is expressed as a larger wavelength or lower frequency.

But with r held constant and M increased, I expected the energy loss of the photon to be increased at r. The photon now travels through a stronger gravitational field and should lose more energy than when travelling through a weak gravitational field.

But the equation above tells me that if r is held constant and M increased, then the gravitational redshift is reduced.

Where am I going wrong?