Light ray falls at normal incidence on the first face of an equilateral prism and emergres gracing the second face. What is the angle of deviation? What is the refractive indec of the material of the prism?

Explanation

The given situaton is shown in the figure.
Here, `A - 60^(@) : l_(1) = 0^(@), l_(2) = 90^(@)`
Equation for angle of deviation.
`d = i_(1) + l_(2) - A`
Substituting the values, `d = 0^(@) + 90^(@) - 60^(@) = 30^(@)` The light inside the prism must be falling on the second face at cirtical angle as it graces the boundary. Equation for cirtical angle is, `sini_( c) = (1)/(n)`
`n=(1)/(sini_(c )):n=(1)/(sin30)=(1)/(1//2)=2`