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The wavelength of a 1 keV photon is 1.24 × 10⁻⁹ m. What is the frequency of 1 MeV photon?

1. 1.24 × 10¹⁵
2. 2.4 × 10²⁰
3. 1.24 × 10¹⁸
4. 2.4 × 10²³

Correct answer: 2.4 × 10²³

Solution

The energy of a photon is related to its frequency by E = hν. For a 1 MeV photon, E = 1 MeV = 1.6 × 10⁻¹³ J. Using h = 6.63 × 10⁻³⁴ J·s, ν = E/h = (1.6 × 10⁻¹³) / (6.63 × 10⁻³⁴) = 2.4 × 10²³ Hz.

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