Question

If light has no mass why is it affected by gravity

Answer 1

Light has a mass of photon.

BTW, light is not affected by normal gravity..

expect black whole

Answer 2

Since light has no mass, how can it be trapped by the gravitational pull of a black hole? Newton thought that only objects with mass could produce agravitational force on each other. According to Newton's theory, the forceof gravity should not affect light.