Question

For a common emitter amplifier, the audio signal voltage across the collector resistance $2 \, k\Omega $ is $2 \, V$ . If the current amplification factor of the transistor is $200$ , and the base resistance is $1.5 \, k\Omega $ , the input signal voltage and base current is

• A. $0.15V$ and $10μA$
• B. $1.015V$ and $1A$
• C. $0.0015V$ and $1mA$
• D. $0.0075V$ and $5μA$

Answer 1

Answer: (D)

The collector current
$I_{C}=\beta I_{b}=\frac{2}{2 \times 10^{3}}$
$I_{C}=1\times 10^{- 3}A$
The base current
$I_{b}=\frac{10^{- 3}}{200}$
$I_{b}=5\times 10^{- 6}A$ A
$I_{b}=5\mu A$ and $V_{B}=I_{b}R_{i}=5\mu A\times 1.5k\Omega $ $=0.0075V$