In the following diagram, which bulb out of B1 and B2 will glow and why?

A) In the diagram, diode D1 is in forward bias and diode D2 is in reverse bias. So current will flow through D1, and D2 will not allow the current to flow. So bulb B1 will glow and bulb B2 will not glow. C) When the photodiode is illuminated with light, with energy greater than the energy gap of the semiconductor, then electron-hole pairs are generated due to the absorption of photons, in or near the depletion region. Due to the electric field of the junction, electrons and holes are separated before they recombine; electrons reach the n-side and holes reach the p-side. Electrons are collected on the n-side and holes are collected on the p-side, giving rise to an emf. When connected to an external load, a current flows, whose magnitude depends on the intensity of incident light. The photodiode can be used as a photodetector to detect optical signals.