Magnetism
This lesson builds magnetic fields, electromagnets and electromagnetic effects for GCSE Physics.
Use the core lesson first, then match the exam-board guidance to your school route. Many pupils meet this content through Combined Science as well as Separate Physics.
What you will learn
Exam-board fit
Exact paper labels and specification-point numbering vary by board and cohort, so match this lesson to your school route before using past-paper questions.
Magnet and coil examples supplied on this page
Use the bar magnet, solenoid and wire-in-field examples to practise field direction, electromagnet strength and force reasoning.
Clear explanation
A magnetic field is the region where a magnetic material or moving charge experiences a force. Field lines show direction and relative strength.
A current in a wire creates a magnetic field. A coil of wire carrying current acts like a magnet; this is an electromagnet.
The motor effect happens when a current-carrying wire in a magnetic field experiences a force. Generator effects involve inducing a potential difference when there is relative motion between a conductor and a magnetic field.
Key diagram
Worked examples
Making an electromagnet stronger
A student wraps insulated wire around an iron core and connects it to a cell.
To make the electromagnet stronger, the student can increase the current or add more turns to the coil.
Using an iron core also concentrates the magnetic field.
Quick checks
Choose an answer, then check your thinking.
1. What creates the magnetic field around an electromagnet?
2. How can a simple electromagnet usually be made stronger?
Practice questions
Question 1
State the direction of magnetic field lines outside a bar magnet.
Reveal answer and marking guidance
Answer: From the north pole to the south pole.
Marking: Credit north to south outside the magnet.
Question 2
Name two ways to increase the strength of an electromagnet.
Reveal answer and marking guidance
Answer: Increase the current and add more turns to the coil.
Marking: Credit either of these plus using a suitable iron core.
Question 3
What happens to the magnetic field around a wire if the current is reversed?
Reveal answer and marking guidance
Answer: The direction of the magnetic field reverses.
Marking: Credit reversal of field direction.
Question 4
In the motor effect, what two things must interact to produce a force on a wire?
Reveal answer and marking guidance
Answer: A current in the wire and an external magnetic field.
Marking: Credit current-carrying conductor plus magnetic field.
Exam practice ladder
Answers and marking guidance
The exact practice answers are hidden under each question so you can try first. For this lesson, marks come from using the correct physics model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as transfer, resultant force, acceleration, evidence and uncertainty.
Common mistakes
- Drawing magnetic field lines as crossing each other.
- Forgetting that an electromagnet can be switched off.
- Saying voltage alone creates an electromagnet without current.
- Confusing the motor effect with electromagnetic induction.
Exam-board guidance
All supported routes assess the core physics idea, but they may group topics, practicals and paper wording differently.
AQA GCSE Physics
AQA GCSE Physics: use this lesson for magnetic fields, electromagnets and electromagnetic effects, then check whether your class is taking Separate Physics or Combined Science.
OCR GCSE Physics
OCR GCSE Physics: the core physics idea is shared, but Gateway and Twenty First Century may organise questions differently.
Pearson Edexcel GCSE Physics
Pearson Edexcel GCSE Physics: practise the concept, the equation use and the practical language because questions often connect them.
Eduqas GCSE Physics
Eduqas GCSE Physics: learn the core explanation and practise applying it to unfamiliar contexts, data and practical questions.
WJEC Wales
WJEC Wales: check whether your class is using the current GCSE Physics route or a newer science route, then use this lesson for the shared physics idea.
CCEA GCSE Physics
CCEA GCSE Physics: connect the idea to your unit and remember that practical skills are assessed directly.
Extension challenge
Design a simple investigation into electromagnet strength, naming the independent, dependent and control variables.
Reveal answer
Example answer: A strong extension response names the physics model, uses accurate units and explains why the evidence supports the conclusion.
Next lesson
Next, continue with Physics Practical Skills.