Question

With respect to air critical angle in a medium for light of red colour [l₁] is q. Other facts remaining same, critical angle for light of yellow colour [l₂] will be-

• A. q
• B. More than q
• C. Less than q
• D. ql₁/l₂

Answer 1

Answer: (C)

Less than q

Answer 2

Critical angle = sin^–1$\left( \frac { 1 } { \mu } \right)$ so

q = sin^–1$\left( \frac { 1 } { \mu _ { \lambda _ { 1 } } } \right)$ and q¢ = sin^–1$\left( \frac { 1 } { \mu _ { \lambda _ { 2 } } } \right)$

since $\mu _ { \lambda _ { 2 } }$> $\mu _ { \lambda _ { 1 } }$ so q¢ < q