Electric Charges and Fields Cheat Sheet

Key Definitions

• Electric Charge: Property of matter that causes it to experience a force in an electric field.

• Coulomb (C): SI unit of electric charge.

• Electric Field (E): Force per unit charge experienced by a positive test charge.

• Field Lines: Imaginary lines that represent the direction of the electric field.

Important Concepts

Types of Charges

• Positive Charge: Repels other positive charges, attracts negative charges.

• Negative Charge: Repels other negative charges, attracts positive charges.

Coulomb's Law

• The force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

Electric Field due to Point Charge

• Electric field E created by a point charge Q at a distance r is given by:

• E = k * |Q| / r²

• k: Coulomb's constant (8.99 x 10^9 N m²/C²)

Key Formulas

• F: Force between charges

• q1, q2: Point charges

• r: Distance between charges

E = F / q

• E: Electric field

• F: Force on charge

• q: Test charge

Common Mistakes to Avoid

Common Mistake: Confusing electric field strength with electric force.

Memory Tricks

Tip: "CFE" — Coulomb's law, Force, Electric field. Remember the sequence!

Key Diagrams

   +Q
    |
    |    E
    |---->
    |
   -Q

• Diagram: Electric field direction from positive to negative charge.