Here we apply the law of the concept of reflection then we get the final answer easily.
The angle of incident = angle of reflection
Then, the Angle of the incident =60°
What is reflection?
Reflection is the phenomenon of light rays returning to the source after striking an obstruction.
It resembles the way a ball bounces when we toss it on a hard surface.
Some of the light rays that strike an item are reflected, some of them travel through it, and the remainder are absorbed by the object.
The given values are:Light from a monochromatic source,= 560 nm
The angle of incidence,= 60°
The surface of fused quartz (n),= 1.56
When a light ray does exist on a flat surface, the law or idea of reflection should apply since it includes both the reflected and "normal" light rays at the mirror surface.
According to the above law,Angle of incident = angle of reflection