Learn how electric circuits work
A free course on electricity for beginners. It starts with a battery, a switch and a lamp, and builds up one idea at a time: voltage, current and resistance, then resistors, diodes, capacitors and transistors, and finally measuring and planning real circuits. Every lesson explains its terms the first time they appear and works through examples with real numbers.
Where to start
The lessons are grouped into steps. Start at the beginning, or pick the step that matches what you already know.
Step 1 · First circuits
What a circuit is, how voltage, current and resistance relate, and why parts get warm.
3 lessons
Start with: Electric circuits for beginners: battery, switch and lampStep 2 · Working with resistors
Combining resistors, reading their values, and using them to get the voltage you need.
4 lessons
Start with: Resistors in series and in parallelStep 3 · LEDs, diodes and capacitors
Parts that only conduct one way, and parts that store charge.
3 lessons
Start with: DiodesStep 4 · Switching and timing
Letting a small signal control a bigger load, and making things blink on their own.
2 lessons
Start with: Using a transistor as a switchOn the workbench
Practical skills for real circuits: measuring, planning power and building them safely.
2 lessons
Start with: Using a multimeterReference
Every term used in these guides, explained in one place.
1 lesson
Start with: Glossary
Newest lessons
- Electric circuits for beginners: battery, switch and lampStart learning electricity with a battery, switch and lamp. Follow electric current, then test an open path and a short circuit.
- Power and heatHow much energy a part turns into heat, and how to pick a resistor that can take it.
- PotentiometersA resistor with a knob: use it to set a voltage or to adjust a current.
How the lessons are written
- From the start
- No previous knowledge is assumed. A new word is explained where it first appears, and the glossary collects them all.
- With real numbers
- Each idea is followed by worked examples using common parts: a 9 V battery, a 470 Ω resistor, a red LED. You can check every step.
- Honest about the limits
- Simple rules have exceptions. The lessons say where a formula stops working, and what to watch out for when you build the circuit for real.
- Safety first
- Batteries and parts can get hot. Warnings point out short circuits, overheating and the voltages you should never work with.
Who the course is for
Students who meet circuits in physics class and want a second explanation, adults who want to start with electronics as a hobby, and parents who want to explain to their children why a lamp lights up. The maths never goes beyond multiplying and dividing.
Who writes the lessons
The lessons are written and kept up to date by Mihai Dumitru, a software engineer. You can read more on the About page. If you spot a mistake or a lesson is unclear, please say so through the contact page.
A circuit game from the same author
VoltTrial turns these ideas into circuit puzzles. It is a separate app: the lessons above do not need it.
Explore electricity with circuit puzzles.
Try the VoltTrial browser demo. The full electricity puzzle game for kids, teens and adults is coming to iOS and Android.
