Ohm's Law Calculator
Calculate voltage, current, resistance, and power using V = IR.
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Enter any two of voltage, current, and resistance. Leave the third blank. The calculator solves for the missing value and shows power. Results update live.
About Ohm's Law
Ohm's law, formulated by Georg Simon Ohm in 1827, is the most fundamental relationship in electrical engineering. It states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance: V = IR. Combined with the power equation P = VI, it allows complete analysis of DC circuits. Ohm's law is used in every aspect of electronics, from simple LED circuits to complex power distribution systems.
Frequently Asked Questions
What is Ohm's law?
Ohm's law states that voltage equals current times resistance: V = IR. It is the fundamental relationship in electrical circuits, connecting voltage, current, and resistance.
How many values do I need to enter?
Enter any two of voltage, current, and resistance. Leave one blank. The calculator determines the missing value and computes power.
Does Ohm's law always apply?
Ohm's law applies to ohmic (linear) materials like metals at constant temperature. Non-ohmic components like diodes and transistors do not follow V = IR.