The bandgap in $eV$ of a semiconductor material required to construct an $LED$ that emits peak power at the wavelength of $310nm$ is ____
$($Plank constant $h=4.13567\times {10}^{15}eV-s$ and speed of light $c=2.998\times {10}^{8}m/s)$

Q. The band gap in $\text{eV}$ of a semiconductor material required to construct an LED that emits peak power at the wavelength of $620\text{nm}$ is

$\text{(Plank constant}h=4.13567\times {10}^{-15}\text{eVs}$ $\text{and speed of light}c=2.998\times {10}^8\text{m/s}\text{)}$

Q. The cut-off wavelength $\left(in\mu m\right)$ of light that can be used for intrinsic excitation of a semiconductor material of bandgap $E_g=1.1eV$ is

Q. LED is constructed from $Ga-As-P$ semiconducting material. The energy gap of this LED is $1.9\text{eV}$. Calculate the wavelength of light emitted and its colour.
$[h=6.63\times {10}^{34}\text{J s}\text{and}c=3\times {10}^8{\text{ms}}^{-1}]$

Q. An $LED$ is constructed from a pn junction based on a certain semi-conducting material whose energy gap is $1.9eV$. Then the wavelength of the emitted light is

Q. The threshold wavelength of silver is $3800\mathring{A}$. Calculate the maximum kinetic energy in eV of photoelectron emitted, when ultraviolet light of wavelength $2600\mathring{A}$ falls on it. (Planck's constant, $h=6.63\times {10}^{-34}J.s.$, Velocity of light in air, $c=3\times {10}^{8}m/s$)