Question

A triode has a mutual conductance of $2 \times 10^{- 3}mho$ and an amplification factor of 50. The anode is connected through a resistance of $25 \times 10^{3}$ ohms to a 250 volts supply. The voltage gain of this amplifier is

• A. 50
• B. 25
• C. 100
• D. 12.5

Answer 1

Answer: (B)

25

Answer 2

Using $A_{V} = \frac{\mu}{1 + \frac{r_{p}}{R_{L}}}$and $\mu = r_{p} \times g_{m}$

$\Rightarrow r_{p} = \frac{\mu}{g_{m}} = \frac{50}{2 \times 10^{- 3}} = 25 \times 10^{3}\Omega$

$\therefore A_{v} = \frac{50}{1 + \frac{25 \times 10^{3}}{25 \times 10^{3}}} = 25.$