IP Physics Notes (Upper Secondary, Year 3-4): 14) Magnetism

Study guide30 Sep 2025, 00:00 ZUpdated 30 Nov 2025

Review magnetic materials, field-line patterns, magnetisation methods, and screening strategies for IP magnetism questions.

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Q: What does IP Physics Notes (Upper Secondary, Year 3-4): 14) Magnetism cover?
A: Review magnetic materials, field-line patterns, magnetisation methods, and screening strategies for IP magnetism questions.

Quick recap -- Magnetism revolves around poles, field lines, and how materials respond. Distinguish soft vs hard magnets, master field sketches, and know how to magnetise or demagnetise safely.

The core idea is simple: Magnetism is about poles, field lines, and material response.

Use it as a working check: Like poles repel, unlike poles attract, field lines run north to south outside a magnet, and soft iron is useful when magnetism must switch on and off.

Then go one layer deeper: Use the field-pattern and screening sections to practise drawing lines with arrows, choosing soft or hard magnetic materials, and explaining magnetisation or demagnetisation steps.

Keep your practice loop tight via our IP Physics tuition hub-it links each topic here to quizzes, diagnostics, and WA-style problem sets.

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These notes align with SEAB GCE O-Level Physics (6091) content used in IP programmes (exams from 2026).

Status: SEAB O-Level Physics 6091 syllabus (exams from 2026) checked 2025-11-30 - scope unchanged; remains the reference for these notes.

Laws & Properties of Magnets

Like poles repel, unlike poles attract; forces strongest near poles.
Freely suspended magnet aligns roughly north-south (Earth behaves like a giant magnet: geographic north magnetic south).
Magnetic materials: iron, steel, cobalt, nickel. Non-magnetic: copper, aluminium, plastic, wood.

Magnetic Materials: Soft vs Hard

Type	Examples	Magnetisation	Uses
Soft magnetic	Iron, soft iron alloys

Reviewed by

Chee Wei Jie·Academic Advisor (Physics)

Question cue	Domain change	Material choice	Answer move
Make a temporary magnet	Domains line up while the field is applied.	Soft iron	Use a solenoid or nearby magnet, then say it demagnetises easily when the field is removed.
Make a permanent magnet	Domains are forced into a more lasting alignment.	Steel or hard magnetic material	Use stroking or a direct-current solenoid, then say the material retains magnetism.
Demagnetise a magnet by heating or hammering	Domain alignment is disturbed.	Any magnetised sample	Explain that random vibration or shock reduces the net alignment.
Demagnetise with an alternating-current solenoid	Domains are repeatedly reversed, then left less aligned as the current is reduced.	Magnetised sample	Mention the alternating field and the gradual reduction in current.

Feature to draw	What it means	How to check it	Common trap
Arrow direction	Direction a north-seeking compass pole would point.	Imagine placing a small compass tangent to the field line.	Drawing arrows from south to north outside the magnet.
Line spacing	Relative field strength. Closer lines mean a stronger field.	Check whether the region is near a pole or between unlike poles.	Using even spacing everywhere, even where the field should be stronger.
Shape between unlike poles	Attraction, with lines joining across the gap.	Lines should connect from north to south without crossing.	Leaving a blank gap between unlike poles.
Shape between like poles	Repulsion, with lines bending away from the middle.	Lines from the two north poles or two south poles should not merge into one line.	Drawing connected lines between like poles as if they attract.

Explanation step	What to say	Why it matters	Common trap
Choose the shield material	Use soft iron or another easily magnetised magnetic material.	The shield must provide an easier path for magnetic flux.	Choosing steel because it is a strong permanent magnet.
Describe the field path	Magnetic flux is guided through the shield instead of through the space inside.	This links the material property to the protected region.	Saying the shield "blocks" magnetism like an opaque wall.
Describe the inside region	The field inside the enclosure is much weaker.	Sensitive instruments experience a smaller magnetic effect.	Claiming the field is always exactly zero everywhere inside.
Explain why soft iron is resettable	Soft iron loses most induced magnetism when the external field is removed.	The shield should not become a strong permanent magnet.	Ignoring what happens after the field is switched off.

IP Physics Notes (Upper Secondary, Year 3-4): 14) Magnetism

Laws & Properties of Magnets

Magnetic Materials: Soft vs Hard

Magnetisation & Demagnetisation

Domain-alignment checkpoint

Magnetic Field Patterns

Field-line drawing checkpoint

Worked Example: Drawing Field Between Plates

Magnetic Screening

Magnetic screening explanation checkpoint

Current-Carrying Conductors (Preview of Chapter 15)

Practice Quiz

Key Takeaways

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