Question

Which is the position of minimum deviation in a prism ?

Answer 1

A piece of glass or any other translucent medium with specific angles and plane faces that can be used to analyse and reflect light is called a prism, in the field of optics. The various wavelengths of light move at different rates within the prism, which is how a prism operates. Since the colours of light pass at varying speeds, they bend differently and come out spaced out rather than mixed together.

Complete answer:
The angle formed by the Incident Ray and the Emergent Ray in a prism is known as the Angle of Deviation. The angle of deviation in a prism is determined by the refractive index of the prism. As the refractive index of a prism increases, the greater the angle of deviation.

The smallest angle from which light is bent by an optical element or method is referred to as the minimum deviation. The angle of deviation (represented by $\delta$ ) in a prism decreases as the angle of incidence (represented by $i$ ) increases up to a certain point. The angle of incidence at which the angle of deviation in a prism is the smallest is defined as the prism's minimal deviation spot, and the angle of deviation at which it is the smallest is defined as the prism's minimum angle of deviation.

The prism's location or position of minimum deviation is where the angle of incidence is such that the refracted ray within the prism is parallel to the prism's base. There is just one angle of incidence under which the angle of deviation is the smallest.

Note: It must be noted that, as mentioned above the refractive index of a prism is directly proportional to its angle of deviation. Even the angle of minimum deviation of the prism is related to the refractive index of the prism. The equation is given below:
${n_{21}} = \dfrac{{\sin (\dfrac{{A + {D_m}}}{2})}}{{\sin (\dfrac{A}{2})}}$
Here, the refractive index of a prism is ${n_{21}}$,the angle of minimum deviation is ${D_m}$ and the angle of the prism is $A$.