A free course
Five short lessons build up the fundamentals of electric circuits, one idea at a time — each with its own live diagram you can drag and break. Then a full interactive lab and ten practice questions tie it all together.
Go in order the first time — each lesson leans on the one before it. Every lesson has a small interactive circuit built into the page, so you're never just reading; you're dragging sliders and watching real numbers respond. Budget about 10 minutes a lesson.
What's actually moving in a wire, and why current is a rate, not an amount.
Start → Lesson 21 V = 1 J/C. The idea that makes everything else in this topic make sense.
Start → Lesson 3What resistance does to current, and V = IR in all three rearrangements.
Start → Lesson 4One path, no junctions: same current everywhere, voltages add up.
Start → Lesson 5A junction splits the charge: same voltage on every branch, currents add up.
Start → Lesson 6The step-by-step recipe for mixed series-parallel circuits, worked in full.
Start → The labThe full interactive circuit: guided walkthrough, live sliders, break-the-circuit switches.
Open → PracticeFrom a basic charge calculation up to a full combined circuit. Self-checking.
Practice →