PrepRung
Sign inSign up free

NDA 2021 GAT · General Knowledge · Light and Optics · medium

The refractive index of a glass is the square root of 2. The critical angle for light going from this glass to air is

Single correct option

The refractive index of a glass is the square root of 2. The critical angle for light going from this glass to air is
  1. A. 45 degrees
  2. B. 30 degrees
  3. C. 60 degrees
  4. D. 90 degrees
Show answer and solution

Answer: (A) 45 degrees

Critical angle C satisfies sin C = 1/n = 1/sqrt(2), so C = 45 degrees. 30 degrees would need n = 2 (sin C = 1/2) and 60 degrees would need n = 2/sqrt(3) (sin C = sqrt(3)/2). At 90 degrees sin C would be 1, which requires n = 1 (no denser medium).
Report a mistake

Original question written in the NDA 2021 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake