With increasing biasing voltage of a photodiode,the magnitude of photoelectric current

The semiconductor used for the fabrication of visible LEDs must at least have a band gap of (in $eV$)

In optical fiber communication, an $APD$ semiconductor is used for:

Which of the following semiconductor devices requires a reverse bias to operate?

$A$ $p-n$ photodiode is fabricated from a semiconductor with a band gap of $2.8 \; eV$. Can it detect a wavelength of $6000 \; nm$?

$A$ family uses $8 \; kW$ of power.
$(a)$ Direct solar energy is incident on the horizontal surface at an average rate of $200 \; W$ per square meter. If $20 \%$ of this energy can be converted to useful electrical energy, how large an area is needed to supply $8 \; kW$?
$(b)$ Compare this area to that of the roof of a typical house.