Refraction Through A Prism

Path of the Ray through a Prism

Given:

• Refractive index of the prism:
• Angle of the prism at
• Angle of incidence on face AC: (since the light is incident normally)
• Angle

The path of the ray follows these steps:

1. The ray is incident normally on the face AC of the prism, so the angle of incidence is .
2. The ray passes through the prism without deviation until it reaches the second face AB.
3. The ray refracts at the interface between the two media at the face AB.

To find the angle of refraction at face AB, we apply Snell’s Law at the boundary:

Where:

• is the angle inside the prism
• is the angle of refraction in air

Since the light is passing from a medium with refractive index (the prism) into air with refractive index 1, we can apply Snell’s law to find the angle of refraction:

Thus, using this relation, you can find the angle , the angle of refraction in air.

Deviation Produced by the Prism

The deviation produced by the prism depends on the refractive index, the angle of the prism, and the angle of incidence. The total deviation can be calculated using the following relation:

Where:

• is the angle of incidence at the first surface (which is as the light is incident normally)
• is the angle of refraction inside the prism

Since the refractive index is and the light is passing through a right-angled prism, the angle of deviation can be computed by:

Thus, the angle of deviation produced by the prism is: