A common emitter amplifier circuit, built using an NPN transistor, is shown in the figure. Its dc current gain is $250$, $R_{\mathit{C}}=1\mathrm{ }\mathrm{k\Omega }$ and $V_{\mathit{C}\mathit{C}}=10 \mathrm{V}$ . The minimum base current for ${\mathrm{V}}_{\mathrm{C}\mathrm{E}}$ to reach saturation is