The energy of a photon is given by

  • A. hf
  • B. h divided by f
  • C. hc
  • D. mc squared only

Explanation

Energy is Planck's constant multiplied by frequency, equivalently hc divided by wavelength, so shorter wavelength means more energetic photons. This is why ultraviolet light damages skin while visible light of the same intensity does not. Planck's constant is 6.63 times 10 to the minus 34 joule seconds.

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