Question

What will be the angle of emergence?

Answer 1

Hint: The angle of emergence is equal to angle of incidence in the glass. The law of reflection gives a relationship between reflected light and incident light and the angle of emergence is the angle of light coming out of a medium .The first medium may be air and the medium which is in the middle may be water or a glass slab.

Complete answer:
The Law of reflection
The law of reflection states that when a ray of light reflects through a surface, the angle of incidence is equal to angle of reflection.

The diagram above illustrates the law of reflection
In the diagram you can observe that the ray of light entering the mirror is known as the incident ray (I) and the ray of light that emerges from the mirror is known as the reflected ray(R).at the point of incidence where the ray enters the mirror at that point line can be drawn perpendicular to the surface of mirror . This line is known as a normal line (N) and this normal line divides the angle between the incident ray and the reflected ray into two equal angles. The angle which lies between the reflected ray and the normal is known as the angle of reflection.

In the prism when a ray of light is incident on the surface of a glass prism it will undergo refraction. After refraction the ray of light will bend towards the normal which you can observe in the above diagram. The refracted ray is incident on the other surface of the prism.
For a prism if we change the direction of light and we should be able to get the same result this means that if angle of incidence $(\alpha )$ results in a certain exit angle $\beta$
Angle of deviation it is the angle between the incident angle and refraction angle
When a light ray undergoes minimum deviation then the angle of incidence is equal to the angle of emergence
The angle of minimum deviation is related to refractive index as
$n=\dfrac{\sin ({{\delta }_{m}}+\alpha )}{\sin (\alpha /2)}$
Angle of incidence is equal to the angle of emergence in glass.
When a ray of light undergoes minimum deviation, the angle of incidence is equal to the angle of emergence

Note: Students the angle of emergence is different for glass and prism.so make sure that while answering you considers this point and in case of maximum deviation the angle of incidence and angle of emergence is different .The incident ray ,refracted ray and the normal at the point of incidence lie at the same plane.