The mutual characteristic curves of a triode are as shown in the figure. The cut-off voltage for the triode is.....$V$.

The slope of the plate characteristic of a vacuum tube diode for a certain operating point on the curve is $10^{-3} \text{ mA/V}$. The plate resistance of the diode and its nature are respectively:

Briefly describe the valve in electronics.

For a given triode,$\mu = 20$. The load resistance is $1.5$ times the anode resistance. The voltage gain will be:

The introduction of a grid in a triode valve affects plate current by

$A$ serious drawback of semiconductor devices is: