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Ohm's Law V=IR is simple but powerful. With it you can size fuses, understand heat generation, and design safe basic electrical circuits.
The Formula
V=I×R | I=V÷R | R=V÷I
Standard formula used by professionals worldwide
Worked Example
Step-by-step
Kettle 2200W, 220V supply → I = P÷V = 2200÷220 = 10A → needs 13A fuse
Key Concepts
- Accuracy: Results are as accurate as the inputs you provide
- Units: Always use consistent units throughout your calculation
- Verification: Double-check important calculations before making decisions
- Professional advice: For major financial, health, or structural decisions, consult a qualified professional
Privacy and Security
- All calculations run entirely in your browser
- No data is sent to any server
- No sign-up or personal information required
- Your data stays private — always
Frequently Asked Questions
Why do wires get hot?
Heat = I²R. More current through resistance generates more heat. Thicker wires reduce resistance.
Fuse sizing?
Calculate max current (I=P÷V), choose next fuse size up for safety margin.
Short circuit?
Near-zero resistance makes current dangerously high — why fuses and breakers exist.