Ohm's Law Calculator
Ohm's law states that voltage equals current multiplied by resistance — V = I × R. Give any two of the three and the third follows, and power can be derived from any pair as well.
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Input
Result
Voltage (V) = 12.00 Volts
About
What the Ohm's Law Calculator does
It is the foundational relationship in electronics, and the reason a resistor's value determines current in a circuit. Working out the series resistor for an LED, for instance, is a direct application: subtract the LED's forward voltage from the supply, then divide by the desired current.
How it works
Using the Ohm's Law Calculator
- 1Enter any two of voltage, current and resistance.
- 2The third is calculated using V = I × R.
- 3Power is derived as P = V × I.
- 4Units are labelled throughout — volts, amps, ohms and watts.
- 5Change any value to recalculate.
Use cases
What people use it for
- Sizing a current-limiting resistor for an LED
- Checking a component's power dissipation
- Working out current draw from a supply
- Learning basic circuit theory
FAQ
Frequently asked questions
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