How Circuits Work
Every robot, every phone, every computer runs on the same fundamental principle: electricity flowing through a circuit. Master this foundation and you can understand — and build — almost anything electronic.
1. Key Concepts
Voltage (V)
Think of voltage as "electrical pressure" — how hard the electricity is being pushed. A regular AA battery is 1.5V. A USB port is 5V. Your home outlet is 120V (don't touch!).
Current (A)
If voltage is pressure, current is the flow of electrons — like water flowing through a pipe. Measured in Amperes (A) or milliamps (mA). LEDs typically use about 20mA.
Resistance (Ω)
Resistors are like speed bumps for electricity. They reduce current flow, which protects sensitive components (like LEDs) from burning out. Measured in Ohms (Ω).
The Breadboard
A breadboard is a reusable board with tiny holes that are connected internally. You can push in wires, resistors, and LEDs to build circuits without soldering — perfect for experimenting!
⚡ Ohm's Law: The Golden Rule
One formula rules all electronics:
Voltage = Current × Resistance. Know any two values, and you can find the third!
2. Watch & Learn
Watch this beginner-friendly intro to how circuits work — from the basic concept to building your first simple circuit.
3. Exercise: Circuit or Not?
A circuit must form a complete loop for current to flow. Look at each scenario below — click whether it would be a working circuit or not!
Question 1 of 4
4. Virtual Breadboard: Blink It!
Build the simplest circuit there is right here in your browser. Connect the Battery to the Resistor, the Resistor to the LED, and the LED back to the Battery!
You completed the circuit.
You've Got Voltage! ⭐
You understand the building blocks of every electronic device on the planet. Ohm's Law is yours forever now.
Finish the circuit quiz to unlock this!