How do you calculate the energy of a photon with an electromagnetic wave of wavelength 420 nm?

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Answer 1 · 2017-06-06T06:23:57

The energy of a photon of frequency #nu# is given by,

#E = hnu# where #h# is the Planck's constant.

Also, we have the general relationship for waves,

#nulamda = c# where #lamda# is the wavelength and #c# is the speed of the wave.

This gives, #nu = c/(lamda)#

Plugging it into the expression for energy,

#E = hc/(lamda)#

Thus, plugging in the numerical values,

#E = 4.73 * 10^(-19) J# Or #E = 2.95 eV#