Fleming’s Left-Hand Rule Simulation — ClassAdapt
What the simulation shows
A 3D electromagnet setup showing the motor effect: a copper wire sits horizontally in the gap between two large magnets — a red N pole on the left and a blue S pole on the right. Everything in the scene is physically motivated.
The magnetic field is shown as nine blue arrows filling the gap, all pointing from N to S (left to right). The arrows are arranged in a 3×3 grid across the cross-section of the gap so students can see the field is present throughout the space, not just on the axis.
The current flows through the copper wire in/out of the page, shown by the ⊙ (dot = tip of arrow toward you = out of page) and ⊗ (cross = tail going away = into page) end-cap symbols on each end of the wire. Ten amber particles travel continuously along the wire in the direction of current, making the flow immediately visible and directionally clear. Reversing the current reverses the particles and swaps the symbols instantly.
The wire moves. This is the centrepiece of the simulation. Spring physics drives the wire toward its force equilibrium — when current and field are set, the wire accelerates in the force direction, overshoots slightly, and settles. When a direction is reversed, the wire gets an impulse, springs away, bounces, and settles at the new position. Students watch the wire physically respond to their choices.
The force arrow is a large green arrow (upward) or red arrow (downward) on the wire showing the direction of force. It flips colour and direction simultaneously with the wire’s motion so the cause-and-effect chain is visually immediate.
Labels mode shows three fixed, non-overlapping panels: B field direction (blue, top-right), I current direction (amber, below B), F force direction (green/red, below I), and the left-hand rule reminder box (bottom-left) with the three finger assignments colour-coded to match the arrow colours. The teaching panel (top-left) gives a plain-English GCSE statement of what is happening right now.
Suggested Class Activity
“Can you predict which way the wire will move?”
This is a prediction-first activity rooted in the motor effect (AQA GCSE Physics Topic 7.3). Students use Fleming’s Left-Hand Rule to predict the force direction before testing it in the simulation — the hallmark of scientific thinking at GCSE.
Duration: 25–30 minutes
Level: GCSE Physics / Combined Science Y10–11
Prior knowledge: What a magnetic field is; direction of current; N and S poles
Sequence
1. Observe first, name later (4 min)
Open the simulation with labels off. Ask students to watch the wire for 20 seconds without telling them what the rule is:
“The wire is in a magnetic field. A current is flowing. Look at what happens. What do you notice?”
Students should see: the wire sits higher than the centre line, field arrows point left to right, amber particles flow out of the page. Take one or two observations aloud.
Then ask: “What do you think would happen if I reversed the current?”
Click ⇄ Flip Current. Wire drops. Particles reverse. Let this land without explanation.
“What do you think would happen if I reversed the field as well?”
Click ⇄ Flip Field. Wire rises again. Students have now directly observed:
- Reversing current reverses force
- Reversing field also reverses force
- Reversing both brings the wire back
They have seen the rule before they know its name.
2. The Left-Hand Rule (5 min)
Turn on Labels. Show students the finger legend (top-right panel). Walk through it:
“Hold your left hand flat. Point your index finger in the direction of the field — that’s the blue arrow, N to S, left to right. Now point your middle finger toward you — that’s the current coming out of the page. Where does your thumb point? Up. That’s the force.”
Let students try with their own left hands. Check they’re using the correct hand.
“This is called Fleming’s Left-Hand Rule. It works for any current-carrying wire in a magnetic field. It tells you which direction the wire will be pushed.”
3. Prediction worksheet (12 min)
Students work individually or in pairs through four prediction questions. For each, they: (a) orient the left hand, (b) predict the force direction, (c) test in the simulation, (d) record whether they were right.
| Question | Field direction | Current direction | Predict force | Test |
|---|---|---|---|---|
| A | N → S (left to right) | Out of page ⊙ | ? | |
| B | N → S (left to right) | Into page ⊗ | ? | |
| C | S → N (right to left) | Out of page ⊙ | ? | |
| D | S → N (right to left) | Into page ⊗ | ? |
Expected answers: A = up, B = down, C = down, D = up.
After completing the table, ask: “What pattern do you notice about questions A and D? And B and C?” (Reversing both gives the same result as the original — students often find this surprising.)
4. Exam question (5 min)
“A current-carrying wire is placed between the poles of a magnet. The current flows out of the page and the field points upward. Using Fleming’s Left-Hand Rule, state the direction of the force on the wire.” (2 marks)
Expected answer: Point the index finger upward (field direction) and the middle finger out of the page (current direction) — the thumb points to the left (1 mark), so the wire is pushed to the left (1 mark).
Note: this question uses a different orientation from the simulation (field vertical, force horizontal) — this is deliberate. Students who only pattern-match from the simulation fail here; students who understand the rule succeed.
5. Extension: motors (3 min)
“This effect — a wire being pushed when current flows in a magnetic field — is the basic principle behind every electric motor. In a real motor, the wire is part of a coil that spins because opposite sides of the coil are pushed in opposite directions. The left-hand rule predicts the direction of force on both sides.”
Adaptation notes for ClassAdapt
- Reduce Motion stops the wire animation — useful for students who find the moving wire distracting while writing predictions
- The Labels button acts as a scaffold toggle — lower-attaining students benefit from turning it on during step 2 to see the real-time B/I/F readout while applying the rule
- The ⊙/⊗ end-cap symbols are a strong dual-coding hook for students who have difficulty with abstract “into the page” language — the symbols make directionality concrete and visual
- The bottom strip chips update in real time as students flip directions, providing immediate feedback without requiring the full label mode
- For students who cannot orient their left hand (physical disability), the colour-coded legend in label mode serves as a complete substitute for the physical gesture