What Is Electricity?

One-sentence summary

Electricity is a form of energy that comes from the movement of very small charged particles; in this lesson we will learn what charge is, how electrons flow and the difference between static electricity and flowing electricity.

Why does it matter?

Almost every device around us runs on electricity. Charging a phone, lighting a bulb, driving a toy car's motor and turning on the LEDs on a micro:bit all rely on the same basic idea: the organised movement of charged particles.

As we learn robotics and coding, we will build circuits. To understand why a circuit works, or why it does not, we first need to know what electricity is. This lesson is the foundation for all the electronics lessons that follow.

Electricity is also a powerful form of energy. It is safe with the right sources and dangerous with the wrong ones. That is why it is important to build safe working habits from the very beginning.

What is electricity?

Every object is made of tiny particles called atoms. Inside atoms there are even smaller particles. Two of them matter to us here:

• Electron: A negatively charged particle that can move around outside the atom.
• Proton: A positively charged particle that stays at the centre of the atom.

Charge is the property that lets a particle push or pull other particles. Like charges push each other away and opposite charges pull each other closer. Just as you feel a push when you bring the same poles of two magnets together, charges also repel or attract each other.

The movement of electrons

In some materials, especially metals like copper, electrons can jump easily from atom to atom. When electrons are pushed in at one end, they move towards the other end. This organised movement of electrons is called electric current.

Materials that let electrons move freely are called conductors (metals, wet hands), and materials that block their movement are called insulators (plastic, glass, dry wood). This is exactly why a cable has copper (a conductor) on the inside and plastic (an insulator) on the outside.

An analogy: a water pipe

To picture electricity, imagine a water pipe. The water inside the pipe is like the electrons inside a wire. When you pump water in, it flows from one end to the other. You can think of a battery as that pump: it pushes electrons so they flow around the circuit.

If the pipe is broken or blocked somewhere, the water stops. In the same way, if a circuit is broken, the electrons cannot flow and the device does not work. This analogy is not perfect in every detail, but it is a good start for remembering that current is "something that flows."

Static electricity and flowing electricity

Electricity has two different faces. Both come from the same charge, but they behave differently.

Static electricity

Static electricity is charge that builds up in one place and stays there. The word "static" means "still." When one surface rubs against another, electrons pass from one object to the other, leaving extra charge on one side and missing charge on the other.

Everyday examples:

• When you rub a balloon on your hair and stick it to a wall, the balloon holds on with static charge.
• Hearing a crackle when you take off a jumper in winter, or feeling a small shock when you touch a door handle, is static electricity.

Static electricity usually discharges all at once: the built-up charge suddenly jumps to another object. These little shocks are mostly harmless.

Flowing electricity

Flowing electricity (current) is the continuous, organised movement of electrons around a circuit. This is what powers our devices. Electrons leave the battery, travel through the wire, give off light as they pass through a bulb and return to the battery.

The difference can be summarised like this:

Electricity in everyday life

The battery

A battery is a source that stores chemical energy inside it and turns it into electrical energy. It has two ends: plus (+) and minus (−). Electrons leave the minus end, travel through the circuit and return to the plus end. A single AA battery gives about 1.5 volts; if we connect two of them end to end, we get about 3 volts. These are safe, low voltages that are good for learning.

The bulb and the LED

A bulb or an LED gives off light when current passes through it. As electrons move through a thin wire or a special material, some of their energy turns into light. When we open the circuit, the current stops and the light goes out.

Charging

When a phone or tablet charges, low-voltage electricity is sent into the battery through a USB cable. This energy is stored in the battery as chemical energy. Later, when you use the device, that energy turns back into electricity to run the screen and the processor. So charging is like refilling an "electron store."

Mini activity

In this activity you will only observe, without touching any wall socket. Have an adult nearby.

1. Take a dry plastic ruler or a balloon.
2. Rub the ruler on a woollen cloth (a jumper or a scarf) for 20–30 seconds.
3. Bring the ruler close to some small paper scraps you have torn up in advance.
4. Watch what happens: do the paper scraps jump towards the ruler?
5. Bring the same ruler close to a thin stream of water from a tap (without wetting the ruler). Does the water stream bend slightly?

Write these notes in your notebook:

Experiment: Static electricity by rubbing
Observation 1: The paper scraps ...
Observation 2: The water stream ...
Conclusion: Rubbing built up ... charge on the ruler.

The charge that builds up in this experiment is static electricity. You did not use any battery, socket or cable; the charge came only from rubbing.

Common mistakes

Mixing up static and flowing electricity

A balloon sticking to your hair is not the same as a bulb lighting up. Both come from charge, but one is still and the other is flowing.

Thinking electrons travel very fast

A single electron actually moves quite slowly inside a wire. But the pushing effect spreads along the whole wire almost instantly. That is why a bulb lights up the moment you press a switch; we do not wait for one electron to travel all the way there.

Assuming every material is a conductor

Plastic, glass and dry wood do not conduct electricity. These insulators protect us; that is why the outer cover of a cable is plastic.

Leaving the circuit open

For electrons to flow, the path must be closed (complete) from start to finish. If the circuit is broken anywhere, no current passes and the device does not work.

Safety note

When learning about electricity, safety always comes first.

• Use only low-voltage sources: batteries (for example 2×AA, 3–6 volts), USB, a micro:bit or an Arduino. These are safe for learning.
• Never touch wall sockets, mains electricity or exposed wiring. Mains electricity (the power in home sockets) is very high voltage and dangerous. It is never used in experiments.
• When working with batteries, motors, cutting tools or hot surfaces, an adult should be nearby.
• Connect the plus (+) and minus (−) ends of a battery the correct way. Never join the two ends directly with a wire and cause a short circuit; the battery can heat up.
• Do not crush, pierce or heat lithium batteries. If they get hot or swell, tell an adult.
• Do not use electronic parts with wet hands or on a wet surface. Water conducts electricity.

Lesson summary

• Electricity is a form of energy that comes from the movement of charged particles, especially electrons.
• Like charges repel and opposite charges attract; conductors let electrons through, while insulators block them.
• Static electricity is charge that builds up in one place; flowing electricity is the continuous movement of electrons in a circuit.
• Batteries, bulbs and charging are everyday examples of flowing electricity.
• For safety, use only low-voltage sources, never touch a wall socket and keep an adult nearby.

Check questions

1. What is the name of the particle that creates electric current?
2. What is the difference between a conductor and an insulator? Give one example of each.
3. Is the electricity created by rubbing a balloon on your hair static or flowing electricity?
4. About how many volts does one AA battery give? About how many volts do you get if two are connected end to end?
5. Why do we never experiment with a wall socket or mains electricity?

Answers

1. The electron. The organised movement of negatively charged electrons creates electric current.
2. A conductor is a material in which electrons move easily (example: copper, metal). An insulator is a material that blocks the movement of electrons (example: plastic, glass).
3. Static electricity. Rubbing makes charge build up on the balloon (or ruler) and stay there; it does not flow through a circuit.
4. One AA battery gives about 1.5 volts. Two of them connected end to end (in series) give about 3 volts.
5. Because the mains electricity in a socket is very high voltage and dangerous. For learning we use only low-voltage sources such as batteries, USB and a micro:bit.

Source and verification note

For “What Is Electricity?”, verification focuses on whether the relationship between What is electricity? and An analogy: a water pipe remains consistent across examples. Activities are designed only for low-voltage direct-current circuits; mains electricity is not used. Component values must be rechecked for the actual circuit, and connections should be reviewed with an adult before power is applied.

Next lesson

Voltage, Current and Resistance: We will learn how strongly electricity pushes in a circuit, how much of it flows and how much the flow is resisted.