In a light emitting diode $(LED)$,light is emitted due to:

Statement $-I$: $A$ photodiode operates in reverse bias.
Statement $-II$: 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.

If a semiconductor photodiode can detect a photon with a maximum wavelength of $400\, nm$, then its band gap energy is (Given: Planck's constant $h = 6.63 \times 10^{-34}\, J \cdot s$, Speed of light $c = 3 \times 10^{8}\, m/s$) (in $ eV$)

Consider the following statements $A$ and $B$ and identify the correct answer:
$A$. For a solar-cell,the $I-V$ characteristics lies in the $IV$ quadrant of the given graph.
$B$. In a reverse biased $pn$ junction diode,the current measured in $(\mu A)$ is due to majority charge carriers.

The $V-I$ characteristics of an $LED$ are correctly shown by which graph?

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