Write the difference between intrinsic and extrinsic semiconductors.

Which of the following statements is correct regarding the charge of semiconductors?

If $N_h$ and $N_e$ are the numbers of holes and conduction electrons in an extrinsic semiconductor,respectively,then:

$A$ potential difference of $2\,V$ is applied between the opposite faces of a $Ge$ crystal plate of area $1\,cm^{2}$ and thickness $0.5\,mm$. If the concentration of electrons in $Ge$ is $2 \times 10^{19}/m^{3}$ and mobilities of electrons and holes are $0.36\,m^{2}/(V\cdot s)$ and $0.14\,m^{2}/(V\cdot s)$ respectively,then the current flowing through the plate will be... (in $,A$)

In $n$-type semiconductor,electrons are majority charge carriers,but it does not show any negative charge. The reason is:

At a temperature of $500 \ K$,the intrinsic electron number density $(n_e)$ and hole number density $(n_h)$ in a pure semiconductor are equal to $1.5 \times 10^{16} \ m^{-3}$. Now,by adding indium impurity,the hole density $(n_h)$ increases to $4.5 \times 10^{22} \ m^{-3}$. This doped semiconductor is: