A triode valve has a dynamic plate resistance of 10 k . Determine...

The dynamic plate resistance of a triode valve is given by the ratio of the change in plate voltage to the change in plate current at a constant grid voltage.

$r_p = \dfrac{\Delta V_p}{\Delta I_p}$

Given:

$r_p = 10 \text{ k}\Omega = 10 \times 10^3 \Omega$

Initial plate voltage, $V_{p1} = 200 \text{ V}$

Final plate voltage, $V_{p2} = 220 \text{ V}$

Change in plate voltage, $\Delta V_p = V_{p2} - V_{p1} = 220 - 200 = 20 \text{ V}$

Substituting the values into the formula:

$\Delta I_p = \dfrac{\Delta V_p}{r_p}$

$\Delta I_p = \dfrac{20}{10 \times 10^3}$

$\Delta I_p = 2 \times 10^{-3} \text{ A}$

$\Delta I_p = 2 \text{ mA}$