In an $LED$,visible light is produced by:

The $I-V$ characteristic of an $LED$ is represented by which of the following graphs?

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

Consider a situation in which reverse biased current of a particular $P-N$ junction increases when it is exposed to light of wavelength $\lambda \le 621 \, nm$. During this process,enhancement in carrier concentration takes place due to the generation of hole-electron pairs. The value of the band gap is nearly (in $eV$):

Statement $-1$: $A$ photodiode operates in reverse bias.
Statement $-2$: The fractional change due to the photo-effects on the minority carrier dominated reverse bias current is more easily measurable than the fractional change in the forward bias current.

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $2480 \; nm$ is incident on it. The band gap in $eV$ for the semiconductor is