Moderate

A photon is________________?

Correct answer: C. A quantum of electromagnetic radiation

  • A. A unit of energy
  • B. A positively charged particle
  • C. A quantum of electromagnetic radiation
  • D. A unit of wavelength

Explanation

A photon is the smallest indivisible packet, or quantum, of electromagnetic radiation, with energy E = hf. It is not itself a unit of energy or wavelength, and it has no electric charge. Students may choose a because a photon carries energy, but carrying a quantity does not make it the unit of that quantity.

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