CIE A Level Physics復習筆記19.1.5 Energy Stored in a Capacitor

Category: A-level課程, 教材筆記, 福利干貨 Date: 2022年8月17日上午11:37

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:

6.-Calculating-Energy-Stored-in-a-Capacitor-equation-1

Substituting the charge with the?capacitance?equation Q = CV, the work done can also be defined as:

6.-Calculating-Energy-Stored-in-a-Capacitor-equation-2

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:

6.-Calculating-Energy-Stored-in-a-Capacitor-equation-3

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