Ohm's Law Calculator
Enter any two of the three values — voltage (V), current (I), or resistance (R) — and instantly calculate the third, plus power consumption in watts.
Ohm's Law Explained
The Triangle
V = I × R. I = V ÷ R. R = V ÷ I. Power: P = V × I = I² × R = V² ÷ R. These four relationships describe the behaviour of every resistive electrical circuit.
Everyday Application
A household circuit at 230V with a 10A fuse allows a maximum load of 2,300W. A USB charger at 5V drawing 2A uses 10W. Ohm's law governs everything from LED resistor selection to household wiring.
Limitations
Ohm's Law applies to linear (ohmic) components like resistors. Non-ohmic components like diodes, transistors, and light bulbs (whose resistance changes with temperature) require more complex analysis.
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