E = h(nu)       (energy of a photon = Planck's constant * photon's frequency
    = hc/(lambda)   = Planck's constant * speed of light * photon's wavelength)

These equations give the energy of a single photon of light, and how it relates
either to its frequency or its wavelength.  For reference,
h = 6.63 * 10^-34 Joule sec  and c = 3 * 10^8 m/sec.

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