Study Notes
The energy stored in a capacitor is related to the work done to charge it, represented by the area under a potential-charge graph. The relationship between charge and potential difference is linear, indicating direct proportionality.
- Capacitor — a device that stores electrical energy in an electric field.
Example: Used in electronic circuits to maintain power supply while batteries are being changed. - Potential Difference (V) — the difference in electric potential between two points.
Example: Measured in volts across the plates of a capacitor. - Charge (Q) — the amount of electric charge stored in a capacitor.
Example: Measured in coulombs. - Capacitance (C) — the ability of a capacitor to store charge per unit potential difference.
Example: Measured in farads. - Electric Potential Energy — energy stored in a capacitor, calculated as the area under the potential-charge graph.
Example: Calculated using the formula W = ½ QV.
Exam Tips
Key Definitions to Remember
- Capacitor: A device that stores electrical energy.
- Potential Difference: The voltage across the capacitor.
- Charge: The amount of electric charge stored.
- Capacitance: The ability to store charge per unit voltage.
Common Confusions
- Confusing capacitance with charge.
- Misunderstanding the linear relationship between charge and potential difference.
Typical Exam Questions
- How is energy stored in a capacitor calculated? Use the formula W = ½ QV or W = ½ CV^2.
- What is the relationship between charge and potential difference? They are directly proportional.
- How do you find the energy stored using a graph? Calculate the area under the potential-charge graph.
What Examiners Usually Test
- Understanding of the formulas for energy stored in a capacitor.
- Ability to interpret potential-charge graphs.
- Knowledge of the relationship between charge, potential difference, and capacitance.