Physics

Ohm's Law Explained for Electronics

By SC Editorial 2026-06-01 6 min read

Ohm's Law relates voltage (V), current (I), and resistance (R) in electrical circuits: V = I * R. It is foundational for electronics, physics, and electrical engineering.

The Three Forms

Solve for any variable: V = IR, I = V/R, R = V/I. Try the Ohm's Law Calculator.

Example

12V battery, 4 ohm resistor: I = 12/4 = 3A current flows through the circuit.

Related: Electrical Power

Power P = VI = I^2 * R = V^2/R, measured in watts. Higher voltage or current means more power dissipated.

Going Deeper

Understand voltage, current, and resistance in electrical circuits. This guide connects theory to practice — use the related calculators linked at the bottom to verify each example with your own numbers.

Practical Tips

  • Write down given values and unknowns before opening the calculator.
  • Check units and rounding rules appropriate to your context (class, lab, or business).
  • Compare manual working with the calculator result to build confidence.

Common Mistakes to Avoid

  • Rushing inputs without reading field labels carefully.
  • Confusing similar formulas that use different variables or units.
  • Reporting results with more precision than your inputs justify.
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