How Circuits Work
Understand the unseen flow of electricity by building real, working circuits. Learn to light components, route power on a breadboard, and automate behavior with switches and transistors.
Like Duolingo, but for How Circuits Work. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
A short one: 11 levels across 2 sections, about 22 minutes end to end, roughly 4 days at five minutes a day. It moves through The Working Circuit and Control and Automation. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in How Circuits Work
- A circuit requires a complete, unbroken conductive loop between both terminals of a power source
- Breaking the loop at any point stops current flow everywhere in the circuit immediately
- Charge does not 'pool' or slowly drain out of a disconnected component like water in an open hose
- Voltage is the electrical pressure or push supplied by a source like a battery
- Current is the physical rate or volume of charge moving through the conductors
- Resistance is the physical property that throttles how much current can pass for a given voltage
- A short circuit occurs when a path with negligible resistance connects directly across a power source
- Electricity favors the path of least resistance, bypassing components in the intended circuit
- Near-zero resistance causes massive current spikes, generating rapid, potentially hazardous heat
- LEDs are polarized components that only pass current and glow when oriented in the correct direction (anode/longer leg to positive)
- An unbuffered LED connected directly to a typical power source draws excessive current and burns out instantly
- A resistor must sit in line with the LED to limit the current to safe operating levels
- Resistors introduce intentional opposition to the flow of charge, lowering total current
- The energy restricted by a resistor is converted into a small amount of heat
- Limiting current keeps delicate semiconductor components from overheating and failing
- Inside each breadboard hole sits a tiny spring-metal clip that grips component wires
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives How Circuits Work the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
What happens if you cut the wire on either side of a glowing light bulb?
Get it right to open this lesson and 10 more in the app.
Where How Circuits Work takes you
- 1
The Working Circuit
- Lighting Your First Component
- Prototyping on a Breadboard
- 2
Control and Automation
- Sensing and Directing Current
- Automating with Transistors
2 sections · 4 units · 11 levels. Built to play, not to enroll.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
How Circuits Work is taught in the Bestie style: your friend who just gets it. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start How Circuits Work today.
Download Tomo, search How Circuits Work, and play your first lesson in under a minute.