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JAMB Physics 2007 Question 12

Question 12

Modern Physics

A photon of wavelength 6.0 × 10−7m behaves like a particle of a certain mass. The value of that mass is [h=6.63 × 10−34 Js, c=3 × 108 ms−1]

  1. A.1.1 × 10−35 kg.
  2. B.2.2 × 10−27 kg.
  3. C.3.5 × 10−36 kg.
  4. D.2.2 × 10−35 kg.
Show the answer and explanation

Answer: C (3.5 × 10−36 kg.)

Explanation

For a photon, mc2 = hc/λ, so m = h/(λc) = 6.63 × 10−34 ÷ (6.0 × 10−7 × 3 × 108) ≈ 3.7 × 10−36 kg, closest to 3.5 × 10−36 kg.