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Charging & Discharging
Capacitors
Introduction
When connected to a circuit, a capacitor does not charge or discharge instantly. Instead, the charge, potential difference and current change exponentially over time. Understanding these charging and discharging processes is an essential part of the AQA A Level Physics course and is widely applied in electronic timing circuits, camera flashes and filtering circuits.
AQA A Level Physics Specification: 3.7.3.4 Charging and Discharging Capacitors
What You Need to Know
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Describe how a capacitor charges and discharges through a resistor.
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Explain how charge, potential difference and current vary during charging and discharging.
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Understand that charging and discharging follow exponential behaviour.
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Define the time constant of an RC circuit.
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Calculate the time constant using resistance and capacitance.
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Interpret charge-time, current-time and potential difference-time graphs.
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Explain the significance of one time constant in charging and discharging processes.
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Solve quantitative problems involving RC circuits and exponential decay.
Downloadable Topic Pack
Capacitors Charging and Discharging Topic Pack Exam Questions and Answers
Related Topics
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Capacitors
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Parallel Plate Capacitors
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Energy Stored by Capacitors
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Exponential Change
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Resistance
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