An $LED$ is a $p-n$ junction diode which is

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

The energy band gap of a semiconducting material required to produce a violet (wavelength $= 4000 \, \mathring{A}$) $LED$ is $....... \, \text{eV}$. (Round off to the nearest integer).

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

Identify the correct circuit diagrams for the normal operation from the following.

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?