Solve for Voltage: 0.5A Through 220Ω

This page opens the Ohm's law calculator with 0.5A of current and a 220Ω resistor already filled in — the voltage and power below are computed live on load, from those two values.

Solving for voltage is what you need when you know how much current a component draws (from a datasheet, or a multimeter reading) and want to know the voltage drop across a resistor in series with it: V = I × R gives 0.5A × 220Ω = 110V. The power dissipated, P = VI, comes out to 55W here — a reminder that this pairing of current and resistance is a large-signal example, not a typical low-voltage hobby circuit.

Because the calculator solves from whichever two fields you fill in, you can just as easily start from a known voltage and resistance instead, or from voltage and power — swap in your own numbers and every other field updates instantly.