A circuit containing a power supply V, a resistor R and a capacitor C is constructed in a laboratory as shown in Fig. 1.1.
Fig. 1.1
Define the meaning of the time constant for a discharging capacitor.
The resistor, R in the experiment is fixed at a resistance of 100 Ω and the capacitor, C has a capacitance of 25 μF and is discharging.
Calculate the time constant of the circuit.
A different resistor and capacitor are now added to the circuit from Fig. 1.1 in part (a). The capacitor is discharging and the discharge graph is shown in Fig. 1.2.
Fig. 1.2
Use the graph to state the value of the time constant for this new circuit.
In a different circuit, a switch is used to charge and discharge the capacitor in the circuit shown in Fig. 1.3. The ammeter is ideal.
Fig. 1.3
The time constant of the capacitor is 0.24 ms and the capacitance is 78 × 10–9 F.
Show that the resistance of resistor R is 3.1 kΩ
Did this page help you?