Question

In a triode plate current is $2.5\, mA$ and plate resistance $20\, k \Omega$, amplification of triode is $10$, the load resistance will be :

• A. $5\, k \Omega$
• B. $25\, k \Omega$
• C. $20\, k \Omega$
• D. $50\, k \Omega$

Answer 1

Answer: (C)

$i_{p}=2.5\, mA =2.5 \times 10^{-3} A,\, r_{p}=20 \times 10^{3} \Omega$
$A=10,\, R_{L}=?$
$V_{p}=i_{p} \times r_{p}=50$
$g_{m}=\frac{i_{p}}{V_{p}}=\frac{2.5 \times 10^{-3}}{50}=5 \times 10^{-5}$
$\mu=r_{\dot{p}} \times g_{m}=20 \times 10^{3} \times 5 \times 10^{-5}=1$
$A=\frac{\mu R_{L}}{R_{P}+R_{L}}$ solving $R_{L}=20\, k \Omega$