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JAMB Physics 1999 Question 34

Question 34

Refraction of Light

The velocities of light in air and glass are 3.0 × 108 m s−1 and 2.0 × 108 m s−1 respectively. If the angle of refraction is 30°, the sine of the angle of incidence is

  1. A.0.33
  2. B.0.50
  3. C.0.67
  4. D.0.75
Show the answer and explanation

Answer: D (0.75)

Explanation

sin i/sin r = speed in air ÷ speed in glass = 1.5, so sin i = 1.5 × sin 30° = 1.5 × 0.5 = 0.75.