Ohm's Law Calculator
Ohm's Law is one of the fundamental relationships in electronics and electrical engineering. This calculator allows you to determine voltage, current, or resistance when any two values are known. It is especially useful for amateur radio operators, electronics hobbyists, and anyone designing or troubleshooting DC power systems.
A mobile radio draws 20 amps from a 13.8-volt power supply.
Resistance: 13.8 ÷ 20 = 0.69 Ω
A 100-watt HF transceiver draws 22 amps at 13.8 volts.
Estimated internal resistance: 13.8 ÷ 22 = 0.63 Ω
A cooling fan measures 0.5 amps on a 12-volt battery.
Resistance: 12 ÷ 0.5 = 24 Ω
- Troubleshooting DC power wiring
- Measuring radio current draw
- Verifying battery system performance
- Selecting appropriate resistors
- Arduino and electronics projects
- Bench testing power supplies
- Field repairs
- Emergency communications equipment
This calculator is intended for planning and troubleshooting low-voltage electrical systems. Always disconnect power before making electrical measurements and verify wiring before energizing equipment.