If light has no mass how is it attracted by Black hole

Einstein theorized and experiments have demonstrated that gravity affects the path of light. Mass is not required. It's based on how gravity bends space and time, and light always follows the shortest path between two points in space-time. In the case of a black hole, the event horizon creates a shortest path back toward the singularly, and no path which leads out of it.

The Simple Answer:
Gravity warps space time
Light has to travel through space time, so it is warped aswell.

Light only technically has mass if you think about the equation e=mc^2. So realistically the photon is massless but the energy is not.

Light still has momentum and can therefore be accelerated (by changing direction not speed) by gravity.

It is ASSUMED that photon has no REST mass. THAT IS AN ASSUMPTION, made to simplify the complexity of the mathematics, which may not be FACT. Even a VERY, very small rest mass of photon will have mass at the speed of light, so mass will be attracted by the gravity of a black hole; enough that light from a background object can be bent and lensed by the gravity of a foreground massive object like a black hole. Mass increases with relativistic speed.

http://curious.astro.cornell.edu/blackho…

but light does have mass.
that was proved during a solar eclipse, and it showed that Einstein's theory of relativity was correct.

the proof was that during the eclipse, a picture showed that a star appeared to change it's position.
that was caused by it's light bending slightly as it passed near the sun.

the star appeared slightly farther away from the sun than it really was.
the light coming directly from the star was bent toward the sun.
the light that was farther away was bent and then came to the observer.
not the same as, but kind of like light coming from a mirror.