Refraction through Plane Parallel plates

When a ray light passes through a flat slab of a transparent material, such as a piece of glass plate, the emergent ray is parallel to the incident ray but displaced from it. Consequently, when we look at any object through a glass plate, we see it slightly displaced in position but unchanged.

Snell’s Law

When ray of light travels from air into glass, it bends towards the

normal lines.

Sin1n1=sin2n2

Sample problem

A ray of light from air is incident on a glass plate (n=1.52) at 30.0 degrees and emerges back into the air. Find angle A, and angle B?

A

B

Solution:Given: n of glass = 1.52

n of air= 1.00

Formula

Sin2=sin1n1/n2

Sin2=(sin30)(1.00)/1.52

Sin2=19.2

Sin2=(sin30)(1.00)/1.52

Sin2=19.2

Sin2=(sin19.2)(1.52)/1.00

Sin2=30

Refraction by a prism

The prism normally used in refracting light is a triangular solid with two solid refracting surfaces. The angel between these two refracting surfaces is called a Refracting angle of a prism.

When a ray light from air enters the prism at the first refracting surfaces, the refracted ray is bent toward the normal because the material of the prism is optically denser than air. As it emerges in the second surfaces the light is bent away from the normal.

The angle between the extension of the incident ray and the emerging ray is called the Deviation angle.

A ray light in air passes into normal glass. The glass is in the shape of an equilateral triangle (prism) the angle of the ray (from the normal line) in air is 50degress. Calculate the angle of the ray in the glass?