In a triode value for a grid voltage `V_g=-1.2V` , the phase current `I_p` and plate voltage `V_p` are given `I_p=(-5+0.1 V_0),I_p` in `mA and V_p` in volt . When grid voltage is changed to - 3.2 V at constant plate voltage of 150 V , a plate current of 5 mA is observed , then
Tran conductance inductance `g_m` is

Options

A. `1.5 xx10^3 ohm^(-1)`
B. `2.5 xx10^3 ohm^(-1)`
C. `3.0 xx10^3 ohm^(-1)`
D. `3.5 xx10^3 ohm^(-1)`

Answer

B

Explanation

Vg = -1 . 2 V , then from eqn (i) in Q.70
As `V_p=150 V_p=150 V, i_p=(-5.0+0.1xx150)=10^(-2)A`
with `Vg = -3.2 V and V_p = 150 V`
`i_p = 5xx10^(-3)A`
`:. G_m` (transconductance ) = `((5-10))/((3.2)-(-1.2))`
`= 2.5 xx10^(-3) ohm^(-1)`