Electronic Devices Question 265
Question: On applying a potential of - 1 volt at the grid of a triode, the following relation between plate voltage Vp (volt) and plate current $ I _{p}(\text{in }mA) $ is found $ I _{p}=0.125V _{p}-7.5 $ If on applying - 3 volt potential at grid and 300 V potential at plate, the plate current is found to be 5mA, then amplification factor of the triode is
Options:
A) 100
B) 50
C) 30
D) 20
Show Answer
Answer:
Correct Answer: A
Solution:
At $ V _{g}=-3V,V _{p}=300V $ and $ I _{p}=5mA $ At $ V _{g}=-1V, $ for constant plate current i.e.
$ I _{p}=5mA $ From $ I _{p}=0.125V _{p}-7.5 $
Therefore $ 5=0.125V _{p}-7.5 $
Therefore $ V _{p}=100V $
hange in plate voltage $ \Delta V _{p}=300-100=200V $
Change in grid voltage $ \Delta V _{g}=-1-(-3)=2V $ So, $ \mu =\frac{\Delta V _{p}}{\Delta V _{g}}=\frac{200}{2}=100 $
