Current Electricity Cheat Sheet

Key Definitions

• Current (I): Flow of electric charge; measured in Amperes (A).

• Voltage (V): Electric potential difference; measured in Volts (V).

• Resistance (R): Opposition to current flow; measured in Ohms (Ω).

• Ohm's Law: Relationship between voltage, current, and resistance.

Important Concepts

Ohm's Law

• V = I × R

• Directly proportional: Current increases with voltage, if resistance is constant.

Series and Parallel Circuits

• Series:

• Same current flows through all components.

• Total Resistance: R_total = R1 + R2 + ...

• Parallel:

• Voltage across each component is the same.

• Total Resistance: 1/R_total = 1/R1 + 1/R2 + ...

Key Formulas

• Ohm's Law: V = I × R

• Power: P = V × I

• Energy: E = P × t

• Resistivity: R = ρ × (L/A)

• ρ: Resistivity (Ω·m)

• L: Length of conductor (m)

• A: Cross-sectional area (m²)

Common Mistakes to Avoid

Common Mistake: Confusing series and parallel circuit rules for resistance.

Memory Tricks

Tip: "VIP" — Voltage = Interest (Current) × Price (Resistance)

Key Diagrams

Series Circuit:
 +---[R1]---[R2]---+
 |                  |
 +------------------+
Parallel Circuit:
 +---[R1]---+
 |          |
 +---[R2]---+
 |          |
 +----------+