Question

When a ray is refracted from one medium into another medium, the wavelength changes from $6000 \, Å$ to $4000 \, Å$ . The critical angle for a ray from second medium will be

• A. $\left(cos\right)^{- 1} \left(\frac{2}{3}\right)$
• B. $\left(sin\right)^{- 1} \left(\frac{2}{3}\right)$
• C. $\left(tan\right)^{- 1} \left(\frac{3}{2}\right)$
• D. $\left(sin\right)^{- 1} \left(\frac{2}{\sqrt{13}}\right)$

Answer 1

Answer: (B)

$sin C=\frac{\mu _{R}}{\mu _{D}}=\frac{\lambda _{D}}{\lambda _{R}}=\frac{4000}{6000}=\frac{2}{3}$