When a monochromatic ray of light is passed through an equilateral glass prism, it is found that the refracted ray in glass is parallel to the base of the prism. If ' i ' and ' e ' denote the angles of incidence and emergence respectively, then
When light travels from one medium to another, it undergoes refraction twice in the case of a prism: first when entering the prism and second when exiting it. The path of light inside the prism is parallel to the base, which means that the angle of incidence at the first surface is equal to the angle of emergence at the second surface. Since we are dealing with an equilateral prism, the angles at each corner are 60∘. Let's denote the angle of the prism as A. When the ray inside the prism is parallel to the base, the angle of refraction at the first surface (inside the prism) will be equal to the angle of incidence at the second surface. Let's denote this angle as r (which is also the angle of refraction at the second surface), then according to Snell's Law, where the refractive index of glass is denoted by n : n⋅sin‌(i)=sin‌(r) and n⋅sin‌(e)=sin‌(r) Since the refracted ray in glass is parallel to the base of the prism, the deviation of the ray inside the prism is minimal, and this occurs when r equals A∕2 for an equilateral prism, so r=60∘∕2=30∘ Since the values of sin‌(i) and sin‌(e) are both obtained by multiplying sin‌(r) with the refractive index n, we have sin‌(i)=sin‌(e) Because the sine function is increasing for angles between 0∘ and 90∘, if sin‌(i) equals sin‌(e), the corresponding angles must also be equal, thus i=e Hence, the correct option is: Option Ci=e