Electronic Devices Question 205
Question: With a change of load resistance of a triode, used as an amplifier, from 50 kilo ohms to 100 kilo ohms, its voltage amplification changes from 25 to 30. Plate resistance of the triode is
[MP PET 1986]
Options:
A) 25 kW
B) 75 kW
C) 7.5 kW
D) 2.5 kW
Show Answer
Answer:
Correct Answer: A
Solution:
Voltage amplification $ A _{v}=\frac{\mu }{1+\frac{r _{p}}{R _{L}}} $
$ \Rightarrow 25=\frac{\mu }{1+\frac{r _{p}}{50\times 10^{3}}} $ ……(i) and $ 30=\frac{\mu }{1+\frac{r _{p}}{100\times 10^{3}}} $ ……(ii) an solving equation (i) and (ii), $ r _{p}=25k\Omega .
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