Explain why a solenoid with an iron core produces a stronger magnetic field than a solenoid without an iron core.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A student builds two solenoids that are identical in every way except that one contains an iron core and the other contains no core. Both solenoids carry the same current.
Model answer (4 marks)
A solenoid with an iron core is a magnetic material that becomes an induced magnet when the current flows through the coil. The magnetisation of the iron creates its own magnetic field, which adds to the field produced by the current in the wire. Because magnetic field lines pass through iron more easily than through air, the field is concentrated and the field lines are drawn into the core. The result is a stronger magnetic field inside the solenoid with the iron core than in the solenoid without a core.
Examiner tips
- Use the term "induced magnet" for the iron core
- Explain that the core’s field adds to the coil’s field
- Mention that field lines are concentrated in the core
- Show the overall effect is a stronger field
Common mistakes
- Saying the iron core simply ‘creates a field’ without linking it to the coil’s field
- Confusing the core’s magnetisation with the coil’s current alone
- Ignoring the role of field line concentration
Mark scheme (4 marks)
- Iron is a magnetic material that becomes an induced magnet when placed inside the solenoid
- The iron core produces its own magnetic field that adds to / combines with the field produced by the current in the coil
- Magnetic field lines pass through iron more easily than through air, concentrating the field
- The overall result is a stronger magnetic field inside the solenoid with the iron core compared to the solenoid with no core
Key terms in this question
solenoid · iron core · magnetic field
Related
- All Edexcel GCSE Physics (1PH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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