Key Stage 5
Meaning
Capacitor discharge is the process of releasing the stored energy in a capacitor through a circuit.
About Capacitor Discharge
- The voltage and current also decrease exponentially during discharge.
- The time constant determines how quickly a capacitor discharges.
- A large time constant means a slow discharge, while a small time constant means a rapid discharge.
- Capacitor discharge curves are used to analyze the behaviour of RC circuits.
- Safety precautions are necessary when discharging large capacitors to avoid electric shock.
Formula
The discharge through a resistor follows an exponential decay described by the formula:
- \(π=π_0π^{βπ‘/π πΆ}\)
- \(π=π_0π^\frac{βπ‘}{π πΆ}\)
Where:
π is the charge stored,
π0 is the initial charge stored,
π is the resistance in the circuit,
πΆ is the capacitance of the capacitor
and
π‘ is time
A capacitor's rate of discharge in a circuit is characterised by the time constant π which is given by the formula:
- π = π πΆ
Examples
In a defibrillator, the capacitor discharges its energy quickly to deliver a shock to a patient's heart. In RC timing circuits, capacitors discharge to control the timing intervals.