19.1 Capacitors and Capacitance
Capacitance :
The charge stored per unit potential difference, i.e., C = Q/V
- Capacitors in series have a combined capacitance given by 1/C = 1/C1 + 1/C2 + 1/C3 + ..., while capacitors in parallel have a combined capacitance given by C = C1 + C2 + C3 + ....
19.2 Energy Stored in a Capacitor
- The electric potential energy stored in a capacitor is given by U = (1/2)CV2 or U = (1/2)QV, where C is the capacitance, V is the potential difference, and Q is the charge on the capacitor.
19.3 Discharging a Capacitor
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When a capacitor discharges through a resistor, the potential difference, charge, and current vary with time.
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The time constant τ = RC, where R is the resistance of the resistor and C is the capacitance of the capacitor.
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The charge, current, and potential difference for a discharging capacitor can be modeled using equations of the form x = x0 e(-t/RC), where x represents current, charge, or potential difference.