how does ac plate resistance differ from dc resistance of a triode?

Question

please answer a.s.a.p.

Answer 1

1. the dc resistance is the ratio of the plate supply voltage to the current.
2. the ac resistance is the ratio of delta voltage to a delta current change.
The tube plate circuit does not behave as a "resistor". In a resistor, the ratio of voltage and current is a constant, no matter what the applied voltage or currents are. In a tube, the plate current is controlled by the effective bias on the intervening grid, and is not a direct function of the applied voltage. You can change the plate current without the voltage changing at all, simply by changing the bias. An AC signal on the grid is the equivalent to changing the plate current in response to the instataneous grid voltage.