AP Physics C Electricity & Magnetism

AP Physics C: Electricity & Magnetism delves into the principles of electricity and magnetism, exploring concepts such as electric fields, magnetic fields, and circuits.

Basic Concepts

Electric Charge and Coulomb’s Law

What is Electric Charge?

Electric charge is a fundamental property of matter carried by particles such as electrons and protons. Charges can be positive or negative, and like charges repel while opposite charges attract.

Coulomb’s Law

The force between two point charges is described by Coulomb's Law: \[ F = k_e \frac{|q_1 q_2|}{r^2} \] where \( F \) is the electric force, \( k_e \) is Coulomb's constant (\( 8.99 \times 10^9 \) N·m²/C²), \( q_1 \) and \( q_2 \) are the charges, and \( r \) is the distance between them.

Key Points

  • Electric charge is quantized and conserved.
  • The force acts along the line joining the two charges.
  • The direction of the force depends on the signs of the charges.

Why It Matters

Understanding electric charge is the first step toward grasping how electricity works, from static shocks to the operation of your phone.

Key Formula

\[F = k_e \frac{|q_1 q_2|}{r^2}\]

Examples

  • A balloon rubbed on your hair attracts small pieces of paper due to static electricity.

  • Two protons in an atom repel each other with a force determined by their charges and separation.

In a Nutshell

Electric charges interact via forces described by Coulomb’s Law, forming the basis for all electric phenomena.

Key Terms

Electric Charge
A property of matter that causes it to experience a force in an electric field.
Coulomb's Law
The law that quantifies the electric force between two point charges.