The energy gap for silicon at 300 k is 1.14 ev. (a) find the lowest frequency photon that will promote an electron in silicon from the valence band to the conduction band.

Explanation:

First of all, let's convert the energy gap from eV to Joules:

In order to promote the electron to the conduction band, the electron must absorb a photon with an energy at least equal to the energy gap, so:

where

h is the Planck constant

f is the frequency of the photon

Solving for f, we find the lowest frequency needed:

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