Why that resistor is there

Every LED in this course has had a resistor next to it and nobody has said why. The answer is one measurement and one subtraction — and the meters will show you both.

A free lesson from Ohmwork, played entirely in your browser on a real circuit solver — about 20 minutes.

Play this lesson in your browser — no download, no sign-up, and nothing you build is sent anywhere.

The full Ohmwork workshop — in development for Mac and Windows — carries 64 lessons across five courses, six simulated Arduino boards running real compiled sketches, an oscilloscope, and fault-finding practice.