🧮 NEW: Made simple – start here
The generator effect made simple: notes and questions → making electricity with a magnet, alternators and dynamos, a Free Science Lessons video, and 12 step-by-step questions with answers. (S only, HT)
3 equations, all Higher tier. Each page has 10 real-life ramped questions with full FIFA solutions. Every equation is given on the equation sheet in the exam.
Key: C+S = Combined and Separate | S only = Separate Physics only | HT = Higher tier only
- Motor effect: F = BIl (C+S, HT)
- Transformers: Vₚ/Vₛ = nₚ/nₛ (S only, HT)
- Transformers: VₚIₚ = VₛIₛ (S only, HT)
📝 Notes and questions – Magnetism and electromagnetism
- Magnets and magnetic fields (C+S)
- Electromagnets and solenoids (C+S; devices S only)
- Motors, loudspeakers and the generator effect (HT; motors C+S, the rest S only)
- Transformers and the National Grid (National Grid C+S; transformers S only, HT)
✏️ Key diagrams to draw – Magnetism
12 diagrams with step-by-step pencil-and-label instructions, including magnetic field patterns, solenoids, Fleming’s left-hand rule, the motor and the transformer. Draw the Magnetism diagrams
📚 Everything for Magnetism
- More practice: Waves and magnetism mixed equation practice
- Revise: Fill the gaps: Magnetism · Magnetism mind map guide
- Lessons: Build a Scrapyard Crane
⚠️ Where students lose marks – Magnetism
Common mistakes highlighted in AQA examiners’ reports (2019, 2022 and 2023), in our own words.
- Dynamos, generators and transformers are the hardest “explain” questions on the paper. Learn the chain: the coil rotates and cuts the magnetic field lines → a potential difference is induced → if the circuit is complete, a current flows.
- Don’t mix up a motor and a dynamo. A motor uses a current to make movement (motor effect). A dynamo, generator or microphone uses movement to induce a p.d. (generator effect).
- Dynamo (d.c.) output: the split-ring commutator and brushes swap the connections every half-turn, so the current always goes the same way. Two full turns give FOUR humps on the graph, all on the same side.
- Why is it easier to turn a generator when no current flows? No current → no magnetic field around the coil → no force opposing the rotation.
- Drawing fields: field lines must never cross or touch, and the arrows must all go from N to S. A solenoid’s field outside looks like a bar magnet’s.
- Induced magnets: a magnetic material becomes a magnet in a magnetic field and loses its magnetism when removed. Two rods inside a solenoid repel because LIKE POLES end up next to each other – they are not “charged”.
- Transformer cores are iron because iron is easily MAGNETISED – not because it conducts electricity.
- Fair tests: change only ONE variable at a time. When describing a graph, compare how much it increases over different ranges and mention if it levels off at a maximum.
- F = BIl (HT): convert mA → A, cm → m, and µT or mT → T before substituting.
- Practise Fleming’s left-hand rule – thuMb = Motion (force), First finger = Field (N to S), seCond finger = Current.
Key definitions
Write your answer on paper first, then tap Show answer. Learn the key words – definition questions are quick marks in the exam.
1. What is a magnetic field? (C+S)
Show answer
The region around a magnet where a force acts on another magnet or on a magnetic material.
2. Name four magnetic materials. (C+S)
Show answer
Iron, steel, cobalt and nickel.
3. What is the difference between a permanent magnet and an induced magnet? (C+S)
Show answer
A permanent magnet produces its own magnetic field. An induced magnet becomes a magnet only when it is placed in a magnetic field, and quickly loses most or all of its magnetism when removed. Induced magnetism always causes a force of attraction.
4. Which way do magnetic field lines point, and where is the field strongest? (C+S)
Show answer
Field lines go from the north pole to the south pole. The field is strongest at the poles, where the lines are closest together.
5. What is a solenoid? Describe the magnetic field inside it. (C+S)
Show answer
A coil of wire. When a current flows through it, the magnetic field inside is strong and uniform. Outside, the field is like that of a bar magnet.
6. What is an electromagnet? (C+S)
Show answer
A solenoid with an iron core. The iron core increases the strength of the magnetic field, and the magnetism can be switched on and off with the current.
7. What is the motor effect? (C+S, HT)
Show answer
When a conductor carrying a current is placed in a magnetic field, the magnet and the conductor exert a force on each other.
8. What does each finger represent in Fleming’s left-hand rule? (C+S, HT)
Show answer
Thumb: direction of the force (motion). First finger: direction of the magnetic field (N to S). Second finger: direction of the current.
9. What is magnetic flux density? (C+S, HT)
Show answer
A measure of the strength of a magnetic field. Unit: tesla (T).
10. What is the generator effect? (S only, HT)
Show answer
A potential difference is induced across a conductor when it moves relative to a magnetic field, or when there is a change in the magnetic field around it. If the conductor is part of a complete circuit, a current is induced.
11. How does a transformer work? (S only, HT)
Show answer
An alternating current in the primary coil produces a changing magnetic field in the iron core. This changing field passes through the secondary coil and induces an alternating potential difference across it.
12. What is the difference between a step-up and a step-down transformer? (S only, HT)
Show answer
A step-up transformer has more turns on the secondary coil than the primary, so it increases the p.d. A step-down transformer has fewer turns on the secondary coil, so it decreases the p.d.
