• Angle of minimum deviation, δm = 30°


• Angle of prism, A = 60°

The formula to calculate the refractive index of prism material is given by:

n = (sin[(A+δm)/2]) / (sin(A/2))


Substituting the given values in the above formula, we get:

n = (sin[(60+30)/2]) / (sin(60/2))

n = (sin(45)) / (sin(30))

n = 1.414 / 0.5

n = 2.828

Therefore, the refractive index of the prism material is 2.828.


The angle of minimum deviation is the angle at which the deviation produced by the prism is minimum. It can be measured by rotating the prism and observing the position of the incident and emergent rays.

The refractive index of a prism material is the ratio of the sine of the angle of incidence to the sine of the angle of refraction. In this case, the angle of incidence and the angle of refraction are not given directly. However, we can use the angle of minimum deviation to calculate the refractive index.

The angle of minimum deviation is related to the angle of incidence and the angle of refraction by the formula:

δm = (A+r1) - (r2)

where A is the angle of the prism, r1 is the angle of incidence and r2 is the angle of refraction.

By using the formula for the angle of minimum deviation, we can calculate the angle of refraction for a given angle of incidence. Then, we can use the formula for the refractive index to calculate the refractive index of the prism material.

In this case, we know the angle of minimum deviation and the angle of the prism. Therefore, we can directly use the formula for the refractive index to calculate the refractive index of the prism material.