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Physics · Magnetism and electromagnetism
Electromagnetism
Describe the magnetic field around a wire carrying a current and in a solenoid, and explain how the strength of the field can be changed.
Teacher resources
The teacher copies: slides with the questions built in, the answers, and anything else attached to this lesson for whoever is teaching it.
- Electromagnetism - Teacher Slides.pptx Teacher The lesson slides with the teacher's notes on each slide, and every question and mark scheme built in. Built from the lesson script on 30 September 2026. View
- Electromagnetism - Teacher Notes.docx Teacher The complete notes with the teacher's notes and every model answer in full. Built from the lesson script on 30 September 2026. View
Student handouts
The same files the students see, to print or hand out.
- Electromagnetism.pptx Built from the lesson script on 30 September 2026. View
- Electromagnetism - Completed Notes.docx The full notes for the lesson, to revise from. Built from the lesson script on 30 September 2026. View
- Electromagnetism - Exam Questions.docx Built from the lesson script on 30 September 2026. View
Warm-up
Answer each one, then check.
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1
What is an electric current?
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A flow of charge
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2
What is a circuit?
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A complete loop for current to flow round
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3
What is a coil of wire called?
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A solenoid
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4
Name a magnetic material.
Show answerHide answer
Iron
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5
What does a battery do?
Show answerHide answer
Provides a potential difference
Learning Objectives
- 1Describe the magnetic field around a straight wire carrying a current.
- 2Explain how the field changes with current and distance.
- 3Describe the field of a solenoid and compare it with a bar magnet.
- 4Explain how to increase the strength of a solenoid's field and how an iron core affects it.
- 5Describe an electromagnet.
CURRENT AND MAGNETISM
When a current flows in a wire it produces a magnetic field around the wire. The field is stronger with a bigger current and closer to the wire.
The field lines around a straight wire are concentric circles. Reversing the current reverses the direction of the field.
Fields Around a Wire and a Solenoid
A solenoid's field looks like a bar magnet's field.
Changing the Strength
Learn what makes a stronger field.
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Bigger current
Effect: Stronger field
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More turns of wire in the coil
Effect: Stronger field
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Iron core inside the solenoid
Effect: Much stronger field
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Reverse the current
Effect: Field direction reverses
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Move further from the wire
Effect: Weaker field
Making an Electromagnet
Describe how to make a strong electromagnet.
Show the solutionHide the solution
- 1 Wind a coil Many turns of insulated wire round an iron core (nail)
- 2 Connect to a cell Current in the coil magnetises the core
- 3 Increase the strength More turns, larger current, or an iron core
AnswerCoil with an iron core and a large current.
Why Use an Electromagnet?
Give two advantages of an electromagnet over a permanent magnet.
Show the solutionHide the solution
- 1 Switch on and off The field disappears when the current is turned off
- 2 Change the strength Change the current to change the field
AnswerIt can be switched off and its strength controlled.
Uses
Where are electromagnets used?
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Scrapyards
Lift and drop scrap iron.
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Electric bells
Current magnetises an iron core that attracts a hammer.
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Relays
A small current switches a large current.
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Maglev trains
Strong electromagnets lift and move the train.
Build One
Wrap insulated wire round a nail and connect it to a cell. Count how many paper clips it picks up with 10, 20 and 30 turns.
1. Keep the current the same.
2. Do not leave it connected: the wire gets hot.
A good answer shows: More turns pick up more paper clips. Stop current flowing and the clips drop.
Can I...?
- 1Describe the field round a wire.
- 2State that the field circles the wire.
- 3Say what a solenoid is.
- 4Compare with a bar magnet.
- 5List ways to strengthen the field.
- 6Say what an iron core does.
- 7Describe an electromagnet.
- 8Give uses.
Summary & Exam Focus
- Current produces a magnetic field.
- More turns, more current or an iron core gives a stronger field.
- A solenoid field is like a bar magnet's field.
- Reversing the current reverses the field.
Exam focus
State two ways to increase the strength of an electromagnet. (2 marks) (2 marks)
Number of turns, current, iron core.
Key terms
The vocabulary this lesson expects you to use. Each one is linked from the first place it appears above.
- Electromagnet
- A solenoid with an iron core that is magnetic only when a current flows.
- Solenoid
- A coil of wire.
- Magnetic field
- The region around a magnet or current where a force acts on magnetic materials.
- Current
- The rate of flow of charge.
- Core
- A piece of iron inside a solenoid.
- Turns
- Loops of wire in a coil.
Questions and answers
10 questions set on this lesson, with the mark schemes and model answers open.
State two ways of increasing the strength of the magnetic field of a solenoid.
Mark scheme — 2 marks available
- One way — 1 mark
- A second way — 1 mark
Model answer
Increase the current. Increase the number of turns. Put an iron core inside the coil. (any two)
Describe the magnetic field around a straight wire carrying a current.
Mark scheme — 2 marks available
- Circles around the wire — 1 mark
- Weaker with distance — 1 mark
Model answer
The field lines are concentric circles around the wire, and the field gets weaker further from the wire.
Explain why a solenoid with an iron core is used in a scrapyard to lift cars and then drop them.
Mark scheme — 3 marks available
- Iron core strengthens the field — 1 mark
- Electromagnet only works when a current flows — 1 mark
- Switching off releases the car — 1 mark
Model answer
The iron core makes the magnetic field much stronger so it can lift heavy iron. The magnet can be switched off by turning off the current, so the car is released.
Describe the magnetic field of a solenoid and explain how it is similar to the field of a bar magnet.
Mark scheme — 3 marks available
- Lines pass through and loop round outside — 1 mark
- Same shape as a bar magnet with two poles — 1 mark
- Strong and uniform inside the coil — 1 mark
Model answer
Field lines pass through the coil and loop round outside from one end to the other. The shape is the same as a bar magnet, with a north and a south end. Inside the coil the field is strong and uniform.
A student increases the current in a solenoid. Explain what happens to the field and to the number of paper clips the solenoid can lift.
Mark scheme — 3 marks available
- Field is stronger — 1 mark
- Greater force on the paper clips — 1 mark
- More clips lifted — 1 mark
Model answer
The field gets stronger. The solenoid exerts a greater force on the paper clips so it can lift more of them.
A current in a wire produces a...
Why: Electromagnetism.
An iron core in a solenoid makes the field...
Why: Iron is magnetic.
Reversing the current reverses the field...
Why: Direction changes.
A coil of wire is called a...
Why: Solenoid.
An electromagnet can be switched off by...
Why: No current, no field.