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In common emitter amplifier, a change of $0.2 \mathrm{~mA}$ in the base current causes a change of $5 \mathrm{~mA}$ in the collector current. If input resistance is $2 \mathrm{k} \Omega$ and voltage gain is 75 , load resistance used in the circuit is
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The correct answer is:
$6 \mathrm{k} \Omega$
$$
\beta=\frac{\Delta \mathrm{I}_{\mathrm{C}}}{\Delta \mathrm{I}_{\mathrm{b}}}=\frac{5}{0.2}=25
$$
Voltage gain, $A_v=\beta \frac{R_L}{R_i}$
$$
\therefore \mathrm{R}_{\mathrm{L}}=\frac{\mathrm{A}_{\mathrm{v}} \mathrm{R}_{\mathrm{i}}}{\beta}=\frac{75 \times 2}{25}=6 \mathrm{k} \Omega
$$
\beta=\frac{\Delta \mathrm{I}_{\mathrm{C}}}{\Delta \mathrm{I}_{\mathrm{b}}}=\frac{5}{0.2}=25
$$
Voltage gain, $A_v=\beta \frac{R_L}{R_i}$
$$
\therefore \mathrm{R}_{\mathrm{L}}=\frac{\mathrm{A}_{\mathrm{v}} \mathrm{R}_{\mathrm{i}}}{\beta}=\frac{75 \times 2}{25}=6 \mathrm{k} \Omega
$$
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