Make the connection

Ohm’s law & power, explained.

Voltage provides an electrical potential difference. Current through an ohmic resistor is voltage divided by resistance. Electrical power is energy transferred per unit time: P = VI = V²/R.

The relationship to remember

V = IR · P = VI

A worked example

With 12 V across 100 Ω, current is 0.12 A and power is 1.44 W.

Inside the default experiment

I = V/R = 12/100 = 0.12 A.
P = VI = 12 × 0.12 = 1.44 W.

When this model applies

Ideal DC voltage source and an ohmic resistor with constant resistance; wires have zero resistance.

Make a prediction. Then test it.

Double the voltage. What happens to current? What happens to power?

Try the interactive experiment ↗

A little question. A clearer picture.

Frequently asked questions

Wondering about the why? Start here.

What happens when resistance increases?

At fixed voltage, current decreases because I = V/R. Power also decreases as V²/R.

Why is zero resistance not allowed?

An ideal source connected across zero resistance would demand an unbounded current. Real circuits have internal resistance and other limits.