Which wavelength of the Sun is primarily used to generate electric energy in solar cells?

An $LED$ (Light Emitting Diode) is constructed from a $p-n$ junction based on a certain $Ga-As-P$ semiconducting material whose energy gap is $1.9\, eV$. What is the wavelength of the emitted light?

$LED$ is constructed from $GaAsP$ semiconducting material. The energy gap of this $LED$ is $1.9\, eV$. Calculate the wavelength of light emitted and its colour.
$[h = 6.63 \times 10^{-34} \, Js$ and $c = 3 \times 10^{8} \, ms^{-1}]$

What are the ideal materials for the fabrication of a solar cell? Give the criteria for their selection.

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

$A$ $p-n$ photodiode is made of a material with a band gap of $2.0\, eV$. The minimum frequency of the radiation that can be absorbed by the material is nearly: