Magnetism
Lesson overview
This lesson introduces the core physics idea, the useful equipment and the calculation or data skills used on this page.
What you will learn
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.
Magnetism and electromagnetism infographic
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.
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.
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.
Exam-board guidance
Short board notes only. Learn the core physics above first.
AQA GCSE Physics
AQA GCSE Physics: often rewards clear physics explanations, correct equations, units and practical evidence for magnetic fields, electromagnets and electromagnetic effects.
OCR GCSE Physics
OCR GCSE Physics: often values precise definitions, clear working, graph interpretation and links between models and evidence.
Pearson Edexcel GCSE Physics
Pearson Edexcel GCSE Physics: often combines the concept with equation use, data handling and practical interpretation.
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: often expects accurate terms, units and evidence-based explanations using the shared physics idea.
CCEA GCSE Physics
CCEA GCSE Physics: connect the idea to your current unit and use the same practical method language your class uses.
Next lesson
Next, continue with Physics Practical Skills.