Ohm's Law and Basic Electrical Math

The Core Principles of Electricity

Whether you're wiring a home theater or studying engineering, Ohm's Law is the foundation of electrical math.

1. Ohm's Law (V = I × R)

Voltage (V) equals Current (I) multiplied by Resistance (R). If you know two of these values, you can always calculate the third.

2. Calculating Power (Watts)

Power (Watts) is calculated by multiplying Voltage by Current (P = V × I). This is how you determine if a circuit will blow a fuse.

3. Battery Life

To estimate how long a battery will last, divide the battery capacity (in Amp-hours) by the load current (in Amps).