The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho.
(a) If the plate voltage in increased by 48 V, and the grid voltage is kept constant, what will be the increase in the plate current?
(b) With plate voltage kept constant at this increased value, how much should the grid voltage be decreased in order to bring the plate current back to its initial value?
Given, rp=8 kΩ, gm=2.5 millimho
a) CASE 1: △VP=48 V, Vg= constant
The dynamic resistance of triode is defined as,
where ΔVp is the change in plate voltage and Vg is the grid voltage and ΔIp is the change in plate current
substituting the values
b) CASE 2: gm=2.5 millimho=.0025 mho, △Ip =6 mA =.006 A
The mutual inductance gm of a triode valve is defined as
1