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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What are your thoughts on this?
 
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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