A2L Item 249

• Description: Identify the correct amount of energy dissipated while charging a capacitor.
• Goal: Reason regarding RC circuits.
• Source: 283 - energy dissipated in RC circuit
• Keywords: Inductors, Energy, Electromagnetism, Circuits, Capacitors, Resistance

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The question for students:

Consider the following circuit. The capacitor is uncharged when switch S is closed at t = 0. During the charging process the total energy dissipated in the resistor is:

1. V^2^/R
2. CV^2^/2
3. QV
4. V/RC
5. none of the above

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Commentary for teachers:

Answer

(2) Students should recognize that if the capacitor ultimately is charged to Q, the total work done by the battery is QV. Half of this is stored in the capacitor and half is dissipated in the resistor.

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