Calculating Material Bandgap Using Quantum Theory

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Quantum theory says that the energy, E , (in eV) of a photon of wavelength λ is E = hc/eλ, where h is Planck's Constant, c is the velocity of light and e is the charge on an electron. Calculate the bandgap of a material which absorbs electrons shorter than 500nm.
 
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This one's easy. Just plug in all the numbers and you have your bandgap. Then use the values for the next two parts to the question.
 

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