3 · Electricity & simple circuits
Every robot runs on electricity, so let's make it simple. Electricity is the flow of tiny charged particles (electrons) through a material. To make that flow do something useful, you build a circuit — a complete loop that the electricity can travel around.
A basic circuit needs three things:
- A power source — a battery, which pushes the electricity. (The "push" is called voltage.)
- A path — wires for the electricity to flow through. (The flow itself is called current.)
- A load — something useful that the electricity powers, like a light bulb, a buzzer, or a motor.
The key rule: the loop must be closed (complete). If there's any gap — a switch turned off, a loose wire — the electricity can't flow and nothing happens. A switch is just a controlled gap: closing it completes the loop and turns the load on; opening it breaks the loop and turns it off. That on/off idea will come back when we talk about coding.
A helpful picture: think of electricity like water in a pipe. Voltage is the water pressure pushing it along, and current is the amount of water flowing past. Too much current through a thin wire is like too much water through a thin pipe — things can overheat, which is exactly why circuits include safety parts.
The micro:bit, a popular beginner board, is built around exactly these ideas: it has metal pins along its bottom edge and "a 3 volt power pin" you can use to power small external parts you add to a circuit (Micro:bit Educational Foundation, n.d.).
Try this (household items). With an adult's help, make a simple circuit using a single AA or AAA battery, a small flashlight bulb (or a low-voltage LED with a resistor from a kit), and two short pieces of wire or aluminum foil. Touch the wires to complete the loop — the bulb lights. Break the loop — it goes dark. You just built a switch with your fingers. Safety: use only a small battery, never a wall outlet.
Check yourself. What three parts does a basic circuit need, and why must the loop be "closed"?
Sources
Micro:bit Educational Foundation. (n.d.). micro:bit features overview. https://microbit.org/get-started/features/overview/