In an insulator,the forbidden energy gap between the valence band and conduction band is of the order of

If the lattice constant of this semiconductor is decreased,then which of the following is correct?

$A$ piece of copper and a piece of germanium are cooled from room temperature to $80 \text{ K}$. Then, which one of the following is correct?

The band diagrams for three different semiconductors are shown in the figure below. Starting from the left to the right,identify the types of semiconductors they represent.

Electrical conductivity of insulators is

The forbidden energy gap in $Ge$ is $0.72\,eV$. Given,$hc = 12400\,eV\cdot\mathring{A}$. The maximum wavelength of radiation that will generate an electron-hole pair is..........$\mathring{A}$.