Question

Angle of glass prism is ${60}^{\circ }$ and refractive index of the material of the prism is 1.414,then what will be the angle of incidence, so that ray should pass symmetrically through prism

• A. ${38}^{\circ }{61}^{\prime }$
• B. ${35}^{\circ }{35}^{\prime }$
• C. ${45}^{\circ }$
• D. ${53}^{\circ }{8}^{\prime }$

Answer 1

The correct option is C ${45}^{\circ }$

incident ray and emergent ray are symmetrical in the cure, when prism is in minimum deviation position.
Hence in this condition $\mu =\frac{sini}{sin\frac{A}{2}}\Rightarrow sini=\mu sin\left(\frac{A}{2}\right)\Rightarrow sini=1.414\times sin{30}^{\circ }=\frac{1}{\sqrt{2}}\Rightarrow i={45}^{\circ }$