Question

Light travels from an optically denser medium 'A' into the optically rarer medium 'B' with speeds 1.8 × 10⁸ m/s and 2.7 × 10⁸ m/s respectively. Then critical angle between them is ______.

(µ₁ and µ₂ are the refractive indices of media A and B respectively.)

Options

• `tan^-1(2/3)`

• `sin^-1(3/4)`

• `sin^-1(2/3)`

• `tan^-1(3/4)`

Answer 1

Light travels from an optically denser medium 'A' into the optically rarer medium 'B' with speeds 1.8 × 10⁸ m/s and 2.7 × 10⁸ m/s respectively. Then critical angle between them is `underline(sin^-1(2/3))`.

Explanation:

`mu_A/mu_B=""_Bmu_A=V_B/V_A=(2.7xx10^8)/(1.8xx10^8)=3/2`

`""_Bmu_A=1/sinC`

`therefore3/2=1/sinC`

`thereforesinC=2/3`

or `C=sin^-1(2/3)`