Ohm's law & power wheel
| To find | From V and I | From I and R | From V and R |
|---|---|---|---|
| Voltage V | — | I × R | — |
| Current I | — | — | V ÷ R |
| Resistance R | V ÷ I | — | — |
| Power P | V × I | I² × R | V² ÷ R |
The two you actually need to remember: V = I × R and P = V × I. Everything above is algebra on those. Voltage in volts, current in amps, resistance in ohms, power in watts.
Worked example: 120 V, 48 Ω → I = 120 ÷ 48 = 2.5 A, P = 120 × 2.5 = 300 W.
Drill these until the rearranging is automatic on the Ohm's law practice page.
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