Through a semiconductor,an electric current is due to the drift of

If the number of holes and electrons are represented by $n_h$ and $n_e$ respectively,then which of the following is correct for an intrinsic semiconductor?

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

In an $N$-type $Ge$ semiconductor,the mobility of electrons is $5000 \ cm^2/V \cdot s$ and the conductivity is $5 \ mho/cm$. If the effect of holes is negligible,what is the concentration of impurity atoms?

$A$ $N-$ type semiconductor is

In an intrinsic semiconductor,the density of conduction electrons is $7.07 \times 10^{15} \, m^{-3}$. When it is doped with indium,the density of holes becomes $5 \times 10^{22} \, m^{-3}$. Find the density of conduction electrons in the doped semiconductor.