AP Physics C: Electricity and Magnetism

Advanced Placement Physics C: Electricity and Magnetism with calculus applications.

Advanced Topics

Capacitance and Dielectrics

What is Capacitance?

Capacitance measures a system’s ability to store electric charge. It’s defined as the ratio of charge to voltage:

\[ C = \frac{Q}{V} \]

Parallel Plate Capacitors

For two parallel plates,

\[ C = \varepsilon_0 \frac{A}{d} \] where \( A \) is plate area and \( d \) is the distance between them.

Dielectrics

Inserting a dielectric material between the plates increases capacitance by reducing the electric field, allowing more charge storage for the same voltage.

Calculus Connection

When voltage or charge changes with time, calculus helps us analyze how energy is stored and released.

Real-World Application

Capacitors are everywhere in electronics, from camera flashes to tuning circuits!

Key Formula

\[C = \varepsilon_0 \frac{A}{d}\]

Examples

  • Calculating the capacitance of a capacitor filled with glass.

  • Determining energy stored in a defibrillator’s capacitor.

In a Nutshell

Capacitance measures how much electric charge can be stored, and dielectrics boost this ability.

Key Terms

Dielectric
An insulating material that increases a capacitor’s capacitance by reducing the electric field.
Capacitance
The ability of a system to store electric charge per unit voltage.