Charges on the move

The idea

Moving charges constitute an electric current in a circuit, the same current that makes a lamp glow and produces heating and magnetic effects.

Still or moving

Charges on a rubbed balloon stay where they are. Charges in a circuit are different.

Do the charges in a working circuit move?

• Yes, they move round the circuit
• No, they stay still
• They vanish

Compare

Look at the charges on a balloon. Then look at the charges in a circuit.

Charges on the move

On the balloon the charges did not move by themselves. In the circuit they moved, and that made the lamp glow. This movement of charges is an electric current.

When charges move, they constitute an electric current in an electrical circuit. It is the same current that makes a lamp glow or produces a heating effect or a magnetic effect.

Notes

Moving charges in a circuit are an electric current. The same current makes a lamp glow and produces heating and magnetic effects.

Check yourself

Charges that move in a circuit form …

Static charges …

The current that makes a lamp glow can also produce …

What makes the lamp glow in a circuit?

• a static charge. Static charges do not move by themselves.
• a magnet. Moving charges form an electric current, not a magnet.
• an electric current — correct. Yes!
• do not move by themselves — correct. Yes!
• always move round a circuit. Moving charges make a current. Static charges stay where they are.
• make a lamp glow. A lamp glows because of a current, which is moving charges.
• only sound. The same current produces heating and magnetic effects.
• a heating effect and a magnetic effect — correct. Yes!
• nothing else. The same current produces heating and magnetic effects.
• Charges standing still. Static charges stay where they are. Moving charges make the current.
• A rubbed balloon. The lamp glows because of the current in the circuit.
• Charges moving through it — correct. Yes!