Question

Two beams of red and violet colors are made to pass separately through a prism (angle of the prism is ${60}^{\circ })$. In the position of minimum deviation, the angle of refraction will be

• A. ${30}^{\circ }$ for both the colors
• B. Greater for the violet color
• C. Greater for the red color
• D. More than ${30}^{\circ }$ for both the colors

Answer 1

The correct option is A ${30}^{\circ }$ for both the colors

minimum deviation is independent of color for a prism
for minimum deviation $r=r^{{}^{\prime }}$

$r+r^{{}^{\prime }}=A=60$

hence $r=r^{{}^{\prime }}=\frac{A}{2}=30$

option $A$ is correct