CIE A Level Physics复习笔记19.1.5 Energy Stored in a Capacitor
Calculating Energy Stored in a Capacitor
- Recall the electric potential energy is the area under a potential-charge graph
- This is equal to the work done in charging the capacitor to a particular potential difference
- The shape of this area is a right angled triangle
- Therefore the work done, or energy stored in a capacitor is defined by the equation:
- Substituting the charge with the capacitance equation Q = CV, the work done can also be defined as:
- Where:
- W = work done/energy stored (J)
- Q = charge on the capacitor (C)
- V = potential difference (V)
- C = capacitance (F)
- By substituting the potential V, the work done can also be defined in terms of just the charge and the capacitance:
Worked Example
Calculate the change in the energy stored in a capacitor of capacitance 1500 μF when the potential difference across the capacitor changes from 10 V to 30 V.
Step 1: Write down the equation for energy stored in terms of capacitance C and p.d V
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