How It Works: Why Electrons Move in a Circuit
Part of Current & Charge — GCSE Physics
This how it works covers How It Works: Why Electrons Move in a Circuit within Current & Charge for GCSE Physics. Revise Current & Charge in Electricity for GCSE Physics with 19 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 13 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 5 of 13
Practice
19 questions
Recall
30 flashcards
⚙️ How It Works: Why Electrons Move in a Circuit
When a battery is connected to a circuit, it creates an electric potential difference between its terminals. This acts like a pressure difference — the negative terminal "pushes" electrons away, while the positive terminal "pulls" them towards it.
Electrons in the wire are free to move (they're called delocalised electrons or conduction electrons). Because the wire is already packed full of these electrons, the push from one end is felt almost instantly at the other — like pushing one marble into a tube full of marbles.
The drift velocity (actual speed of electrons) is extremely slow, but the electrical signal travels at close to the speed of light. This explains why lights turn on instantly even though individual electrons barely move.
Current = flow rate (litres per second through the pipe)
Charge = total volume of water (litres)
Just as water flows continuously around a closed loop of pipes, electrons flow continuously around a closed circuit. The pump (battery) provides the push; the water (electrons) is already in the pipes.
Quick Check: A current of 3 A flows in a circuit for 20 seconds. How much charge passes a point?
Q = I × t = 3 × 20 = 60 Coulombs.