An $LED$ is manufactured using zinc selenide; then it emits:

$A$ solar cell is to be fabricated for efficient conversion of solar radiation to emf using material $A$. The solar cell is to be mechanically protected with the help of a coating using material $B$. If the band gap energy of materials $A$ and $B$ are $E_{A}$ and $E_{B}$ respectively,then which of the following choices is optimum for better performance of the solar cell?

The energy gap of an $LED$ is $2.4 eV$. When the $LED$ is switched $ON$,the momentum of the emitted photons is

Given below are two statements: one is labeled as Assertion $A$ and the other is labeled as Reason $R$.
Assertion $A:$ Photodiodes are used in forward bias usually for measuring the light intensity.
Reason $R:$ For a $p-n$ junction diode, at applied voltage $V$, the current in the forward bias is more than the current in the reverse bias for $|V_z| > |V| \geq V_0$, where $V_0$ is the threshold voltage and $V_z$ is the breakdown voltage.
In the light of the above statements, choose the correct answer from the options given below.

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

$A$ $p-n$ 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: