How Electricity Actually Works

Before symbols and formulas, a picture of what's moving inside a wire.

Every atom has a nucleus surrounded by electrons. In conductive materials like copper, the outermost electrons aren't held tightly — they can drift from atom to atom. Electricity is simply that drifting, given a direction.

A power source, like a battery, pushes electrons out of one terminal and pulls them into the other. Connect a wire between the terminals and you give the electrons a path to flow through — that path is a circuit. Break the path anywhere and the flow stops instantly.

• Electrons flow from the negative terminal, through the circuit, to the positive terminal.
• Older convention ("conventional current") is drawn the opposite way, positive to negative — both describe the same circuit, just from different eras.
• A circuit must be a closed loop. No loop, no current.