Question

The dynamic plate resistance of a triode value is 10 kΩ. Find the change in the plate current if the plate voltage is changed from 200 V to 220 V.

Answer 1

change in plate current $\Delta I = 20 \times 10^{-4} amp$

Explanation:

Given that, $R_p = \textrm{10 K}\Omega$ $= 10^4\Omega$, $V_1 = \textrm{200 Volt}$ and $V_2 = \textrm{220 Volt}$

Dynamic resistance of triode $R_p = (\frac{\Delta V}{\Delta I})_v_g$

where, $\Delta V$ is the change in plate voltage $v_g$ is the grid voltage, $\Delta I$ is the change in plate current

$\Delta I = \frac{\Delta V}{R_p}$

⇒ $\Delta I = \frac{220 - 200}{10^4}$

⇒$\Delta I = 20 \times 10^{-4} amp$.

Answer 2

Change in Plate Current is 2 mA

Explanation:

• Given $r_p = 10 K\Omega = 10^4 \Omega$,  

$V_P_1 = 200\ V, V_P_2 = 220\ V$

• The dynamic resistance of triode is defined as,

$r_p = [(\frac {\Delta V_p}{\Delta I_p}) ]_V_g_=_c_o_n_s_t_a_n_t$

where $\Delta V_p$ is the change in plate voltage and $\Delta V_g$ is the grid voltage and $\Delta I_p$ is the change in plate current

$10^4 = \frac {220 - 200}{\Delta I_p}$

$\Delta I_p = \frac {20}{10^4}$

= 2 mA