Question

If $\beta,R_{L}$ and r are the ac current gain, load resistance and the input resistance of a transistor respectively in CE configuration, the voltage and the power gains respectively are

• A. $\beta\frac{R_{L}}{r}$and $\beta^{2}\frac{R_{L}}{r}$
• B. $\beta\frac{r}{R_{L}}$ and $\beta^{2}\frac{r}{R_{L}}$
• C. $\beta\frac{R_{L}}{r}$and $\beta\left( \frac{R_{L}}{r} \right)^{2}$
• D. $\beta\frac{r}{R_{L}}$ and $\beta\left( \frac{r}{B_{L}} \right)^{2}$

Answer 1

Answer: (A)

$\beta\frac{R_{L}}{r}$and $\beta^{2}\frac{R_{L}}{r}$

Answer 2

: Voltage gain = current gain ×resistance gain

$= \beta \times \frac{outputresis\tan ce}{inputresis\tan ce} = \beta \times \frac{R_{L}}{r}$

Power gain = voltage gain × current gain

$= \beta\frac{R_{L}}{r} \times \beta = \beta^{2}\frac{R_{L}}{r}$