Question

A varying voltage is applied to the clamps AB (Fig. 99) such that the voltage

across the capacitor plates varies as shown in Fig. 100.

Plot the time dependence of voltage across the clamps CD.

Answer 1

It can be seen that during the time interval from 0 to t₀, the voltage across the capacitor is zero, the charge on it is also zero, there is no current through it, and hence U_CD is zero during this time interval (Fig. 221). During the time interval from to to 2t₀, the voltage across the capacitor, and hence the charge on its plates, grows linearly, and hence a direct current passes through the circuit. This means that the voltage U_CD is constant. During the time interval from 2t₀ to 3t₀, the voltage across the capacitor does not change. Hence current does not flow, and U_CD is zero. Finally, during the time interval from 3t₀ to 5t₀, the capacitor is discharged, the current through the resistor is negative and constant, and its magnitude is half

the value of the current during the time interval from t₀ to 2t₀.