What Is Electricity?
Electricity powers almost everything around you. Find out what really moves through a wire, and why it’s slower than you think.
The question
Flip a switch and the light comes on instantly. What actually travels through the wire?
What you’ll discover: what electricity is made of, why it needs a complete path, and why the “stuff” in the wire moves far more slowly than you’d think.
In simple terms
BeginnerCharges on the move
Everything around you is made of tiny particles called atoms. Atoms contain even smaller particles. Two of them matter here:
- Protons carry a positive (+) charge and stay put in the centre of the atom.
- Electrons carry a negative (−) charge. In metals like copper, some electrons are free to wander from atom to atom.
Electricity is what electric charges do, whether they sit still (static electricity) or flow (current electricity). A battery pushes them to flow. Wires give the charges a road to travel on. When the road makes a complete loop, the charges flow, and they carry energy that can light an LED, spin a motor or make a sound.
Think of a bicycle chain. When you push the pedal, every link starts moving at once, so the back wheel turns right away even though each link only moves a little. Electricity in a wire works in a similar way: all the free electrons start drifting together, so energy arrives at the light almost instantly.
Two kinds you already know
Static electricity is charge that builds up and stays in one place, until it jumps. On a dry Lethbridge winter day, shuffle across the carpet and touch a doorknob: that snap is static electricity. In humid air, a thin film of moisture lets charge leak away. In dry air it can’t, so it builds up, which is why shocks are more common in winter. Lightning is static electricity on a giant scale.
Current electricity is charge flowing steadily around a loop, like in a flashlight. That’s what Electronics School is mostly about.
Try it: make some static
Rub a balloon on your hair or a wool sweater for 10 seconds. Hold it near tiny bits of torn paper, or near a thin stream of water from a tap.
Why it works: rubbing moves electrons onto the balloon, giving it extra negative charge. That charge pushes the electrons in the paper slightly away, leaving the near side of the paper a little positive, and that side is pulled toward the balloon. The water stream bends for the same reason.
Go deeper
IntermediateCurrent, charge and direction
Electric current is the rate at which charge flows past a point. It’s measured in amperes (A), or amps. Small electronics use milliamps (mA): 1 A = 1000 mA. A small LED needs about 10 to 20 mA.
Here’s a historical twist: in the 1740s, Benjamin Franklin and others described current as flowing from + to − around a circuit. This is called conventional current, and every circuit diagram still uses it. The electron wasn’t discovered until 1897, and it turned out that in metal wires it’s actually the negative electrons that move, from − to +. Both descriptions give the same answers; just be consistent.
AdvancedCoulombs and drift velocity
Charge is measured in coulombs (C). One electron carries about 1.602 × 10−19 C, so a current of 1 A (one coulomb per second) means roughly 6.24 × 1018 electrons passing each second.
Yet each electron moves surprisingly slowly. Its average drift velocity in a typical copper wire is well under a millimetre per second. The energy travels fast because the electric field that pushes the electrons spreads along the circuit at a large fraction of the speed of light, setting all the free electrons moving almost at once. That’s the bicycle chain idea, made precise.
Quick check
Which particle is free to move through a copper wire?
Electrons. Protons stay locked in the centre of each atom.
Why does the light come on instantly if electrons move so slowly?
All the free electrons in the loop start moving at nearly the same moment, like the links of a bicycle chain, so energy reaches the light almost immediately.
Is a winter doorknob shock static or current electricity?
Static. Charge built up on you and jumped to the doorknob all at once.
Words to know
- Atom
- The tiny building block of all matter.
- Electron
- A tiny particle with a negative charge. Free electrons carry current in metals.
- Current
- The flow of electric charge, measured in amperes (A).
- Static electricity
- Electric charge that builds up in one place.
Learn more
- Science World (Vancouver): Current Electricity: eight hands-on circuit activities
- Alloprof (Québec): Electricity and electrical circuits: a plain-language explainer for students
- Next: Voltage, current and resistance
Electronics School is part of the Discovery Zone. Every activity here runs on small batteries or a USB cable: never wall outlets. The one plug-in tool is the optional soldering iron, set up by an adult.