Question

Plate resistance of two triode valves is 2 KΩ and 4 KΩ, amplification factor of each of the valves is 40. The ratio of voltage amplification, when used with 4 KΩ load resistance, will be

• A. 10
• B. $\frac{4}{3}$
• C. $\frac{3}{4}$
• D. $\frac{16}{3}$

Answer 1

Answer: (C)

$\frac{3}{4}$

Answer 2

Voltage amplification

$A_{V} = \frac{\mu}{1 + \frac{r_{p}}{R_{L}}} = \frac{\mu R_{L}}{R_{L} + r_{p}} \Rightarrow \frac{A_{1}}{A_{2}} = \frac{2 + 4}{4 + 4} = \frac{3}{4}$.