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JAMB Physics 1989 Question 24

Question 24

Refraction of Light

Light of wavelength 5000 × 10−8 cm travels in free space with a velocity of 3 × 108 m s−1. What is its wavelength in glass of refractive index 1.5?

  1. A.3333 × 10−8 cm
  2. B.5000 × 10−8 cm
  3. C.6666 × 10−8 cm
  4. D.7500 × 10−8 cm.
Show the answer and explanation

Answer: A (3333 × 10−8 cm)

Explanation

The frequency stays the same and the speed falls by 1.5 times, so the wavelength also falls: 5000 ÷ 1.5 ≈ 3333 × 10−8 cm.