Chapter 16, Problem 39A

To determine

The evidence for the change in energy.

Explanation of Solution

Introduction:

Photon is a bundle or packet of energy consists of electromagnetic radiations having no rest mass.

When a photon is sent in the gravitational field, velocity of the photon will not change. As momentum is product of mass and velocity, momentum of the photon also remains unchanged.

The frequency and hence the wavelength of the photon is shifted. Because frequency and wavelength are inversely proportional to each other. Hence person observing this effect from outside could say that the photon is bent in the gravitational field.

Conclusion:

There will not be any change in speed and momentum of the photon , only frequency and hence wavelength would be shifted if photon enters the gravitational field.