When an $LED$ is manufactured by using aluminium gallium arsenide $(AlGaAs)$,it emits:

What kind of diode is used as a photo detector?

The following graph represents:

The $I-V$ characteristics of a photodiode for different illumination intensities $I_1, I_2, I_3$ and $I_4$ are shown in the figure. Which of the following represents the maximum intensity?

$A$ photodetector is fabricated from a semiconductor with a band gap $E_g = 0.73 \, eV$. What is the maximum wavelength (in $nm$) it can detect?

$A$ photodiode is a device