Overview, ATL skills, and functional literacy
Statement of inquiry
Invisible magnetic fields can be modeled and investigated to explain how electricity and magnetism are related in natural and technological systems.
ATL skills
- Critical thinking: identify patterns between current and field strength.
- Transfer: connect bar magnets to current-carrying coils.
- Communication: explain magnetic field direction using scientific vocabulary.
- Research: use simulation evidence to support claims.
- Reflection: evaluate how reliable your model or method is.
Functional literacy tasks
- Interpret diagrams, arrows, symbols, and field-line maps.
- Read a simple technical procedure and follow steps safely.
- Use evidence from a table or graph to justify a conclusion.
- Explain how electromagnets are used in real devices.
Magnetic field around a current-carrying conductor
When electric current flows through a straight conductor, it creates a magnetic field around the wire. The field lines form concentric circles centered on the wire.
The direction of the field depends on the direction of the current. A useful model is the right-hand grip rule:
- Point your right thumb in the direction of the current.
- Your curled fingers show the direction of the magnetic field around the wire.
If the current increases, the magnetic field becomes stronger. If the current reverses, the field direction reverses too.
Mini interactive model
Use the controls to explore how current direction and current size affect the field around a wire.
The compass arrow follows the circular magnetic field around the wire.
A current in a wire is reversed. What happens to the magnetic field around it?
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Use the right-hand grip rule to explain how a student can find the direction of the magnetic field around a straight current-carrying wire.
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A circuit diagram shows a wire marked with a dot (•). Explain what that symbol means and predict the field direction using the right-hand rule.
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Electromagnets
An electromagnet is a magnet produced by electric current. A simple electromagnet is made by passing current through a coil of wire. The magnetic field from each loop adds together, creating a stronger magnetic field than a single straight wire.
Electromagnets are often stronger when:
- The current is larger.
- The number of turns in the coil is greater.
- A soft iron core is placed inside the coil.
Electromagnets are useful because they can be switched on and off and their strength can be changed.
Electromagnet strength explorer
Move the sliders to see how current, number of turns, and an iron core affect the strength of an electromagnet model.
Predicted strength: Medium
Which change would usually make an electromagnet stronger?
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Explain two advantages of an electromagnet compared with a permanent magnet.
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A recycling crane must lift steel cans but release them quickly. Explain why an electromagnet is more useful than a permanent magnet for this job.
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Interactive PhET simulations
The simulations are embedded below. If a school browser blocks the embed, use the open buttons.
PhET 1: Magnets and Electromagnets
Suggested focus: compass direction, bar magnet field, current in a coil, number of turns, and strength changes.
PhET 2: Faraday’s Electromagnetic Lab
Suggested focus: relation between changing magnetic field, current, coil setup, and electromagnet behavior.
Using the Magnets and Electromagnets simulation, investigate how changing the current changes the magnetic field around a coil. Record your observations and write a conclusion.
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Use one of the simulations to test the claim: “An iron core always matters more than increasing current.” Do you agree? Justify your answer with evidence from the simulation.
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MYP assessment tasks: Criteria A, B, C, and D
Criterion A: Knowing and understanding
- Define magnetic field, magnetic pole, conductor, and electromagnet.
- Draw and label the magnetic field around a bar magnet and a straight current-carrying wire.
- Explain how the right-hand grip rule helps determine magnetic field direction.
- State three ways to increase the strength of an electromagnet.
Show sample answers / marking support
Possible points: A magnetic field is a region where magnetic forces act. An electromagnet is a magnet created by current in a coil. The right-hand grip rule links current direction to field direction. Strength can be increased by increasing current, increasing turns, or adding an iron core.
Criterion B: Inquiring and designing
- Design an investigation to test how the number of coil turns affects electromagnet strength.
- State the independent, dependent, and controlled variables.
- List apparatus.
- Write a safe, fair-test method.
Show sample design points
Independent variable: number of turns.
Dependent variable: strength of electromagnet, for example number of paper clips lifted.
Controlled variables: same current, same core, same wire type, same testing time.
Method idea: wind different numbers of turns around the same iron nail, keep the current fixed, test how many paper clips are lifted, repeat trials, and average results.
Criterion C: Processing and evaluating
Use the data table below to answer the tasks.
| Turns in coil | Current (A) | Paper clips lifted |
|---|---|---|
| 10 | 1.0 | 3 |
| 20 | 1.0 | 6 |
| 30 | 1.0 | 9 |
| 40 | 1.0 | 11 |
- Describe the pattern in the data.
- State a conclusion.
- Comment on reliability and suggest one improvement.
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Criterion D: Reflecting on the impacts of science
- Describe one useful application of electromagnets in society.
- Explain one benefit and one limitation of using electromagnets instead of permanent magnets.
- Discuss how understanding magnetism helps engineers design safer or more efficient technologies.
- Communicate your response as a short paragraph for a non-scientific audience.
Show sample response guide
Return to the hook question: Why does a compass needle move near a wire carrying electric current? Write a final explanation using the ideas of magnetic field, field direction, and current.