Physics 2003 JAMB Past Questions - Question 38: A ray incident on a glass prism undergoes minimum deviation when the

Correct Answer

D

Explanation

At minimum deviation, it is not observed that light passes symmetrically through, the prism such that the angle of incidence is equal to the angle of emergenceA ray of light incident on a glass prism undergoes minimum deviation when the angle of incidence is equal to the angle of emergence, and the deviation is minimized. This condition occurs when the ray of light is incident on one of the two refracting surfaces of the prism at the so-called "angle of minimum deviation" or "angle of prism."

The angle of minimum deviation is specific to the particular prism and the material it is made of. It is a unique angle at which the deviation of the light ray is minimized. In the case of a glass prism, the angle of minimum deviation typically depends on the prism's refractive index and geometry.

When the angle of incidence is set to this angle of minimum deviation, the light ray will refract at the first surface of the prism, undergo total internal reflection at the second surface (if the angle of incidence is greater than the critical angle), and then refract again as it emerges from the prism. This results in the least deviation of the light ray from its original path.

To calculate the angle of minimum deviation, you would typically use the formula for minimum deviation, which relates the angle of incidence (i), the angle of emergence (e), and the angle of the prism (A):

sin[(A + Dm)/2] / sin(A/2) = n

Where:
- A is the angle of the prism.
- Dm is the minimum deviation.
- n is the refractive index of the material of the prism.

By adjusting the angle of incidence to satisfy this equation, you can achieve the minimum deviation of the light ray as it passes through the prism.