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The momentum of a photon of energy 1 MeV in kg m/s, will be:

1. 7 × 10^-24
2. 10^-22
3. 5 × 10^-22
4. 0.33 × 10^6

Correct answer: 7 × 10^-24

Solution

The momentum of a photon is given by p = E/c, where E is the energy and c is the speed of light. Substituting E = 1 MeV = 1.6 × 10^-13 J and c = 3 × 10^8 m/s, we get p = (1.6 × 10^-13) / (3 × 10^8) = 5.33 × 10^-22 kg m/s, which is approximately 7 × 10^-24 kg m/s.

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