Problem 4
A semiconductor is used to make an LED that emits red light at \(\lambda=630 \mathrm{nm}\) (a) Find the energy gap in eV of the semiconductor. (b) Find the energy in joules of a photon emitted. (c) Find the energy in joules for Avogadro constant number of these photons.
Problem 9
A solar panel has an area of \(50 \mathrm{~m}^{2}\), and it produces an average of 4 \(\mathrm{kW}\) of power. The panel is in a location which receives an average of \(0.085 \frac{\mathrm{W}}{\mathrm{cm}^{2}}\) of optical energy from the sun. Calculate the efficiency of the panel.
