The concentration of electrons in an intrinsic semiconductor is $6 \times 10^{15} \mathrm{~m}^{-3}$. On doping with an impurity, the electron concentration increases to $4 \times 10^{22} \mathrm{~m}^{-3}$. In thermal equilibrium, the concentration of the holes in the doped semiconductor is

Three logic gates are connected as shown in the figure. If the inputs are $A=1$ and $B=1$, then the values of $Y_1$ and $Y_2$ respectively are

If the ratio of electron and hole currents in a semiconductor is $7 / 4$ and the ratio of drift velocities of electrons and holes is $5 / 4$, then ratio of concentrations of electrons and holes will be