Question

An equilateral prism is placed on the prism table of spectrometers in the position of minimum deviation the angle of incidence is ${60}^{\circ }$,the angle of deviation the ray is :

• A. ${90}^{\circ }$
• B. ${60}^{\circ }$
• C. ${45}^{\circ }$
• D. ${30}^{\circ }$

Answer 1

Answer: (B)

${60}^{\circ }$

Equilateral prism

Since in minimum deviation Condition

$i=e{\gamma }_1={\gamma }_2$

${\gamma }_1+{\gamma }_2=A$

$\begin{array}{cc}\delta & =i+e-A\\ & ={60}^{\circ }+{60}^{\circ }-{60}^{\circ }\\ \delta & ={60}^{\circ }\end{array}$

so option $B$ is correct