# Simple Phenomena of Magnetism

> Physics · CIE IGCSE 0625
> Source: https://www.owlsprep.com/study/cie-0625-u4-simple-phenomena-of-magnetism/

This guide covers all Core and Extended content for simple magnetism phenomena in CIE IGCSE Physics 0625 Unit 4, including magnetic properties, field lines, induced magnetism, and solenoid rules for 2026-2028 exams.

**Prerequisites:** [General physical properties of materials](https://www.owlsprep.com/study/cie-0625-u1-physical-properties/)

## Learning objectives

- State properties of permanent magnets and magnetic materials
- Plot and describe magnetic field patterns around bar magnets
- Explain induced magnetism and its properties (Core)
- Describe methods of magnetisation and demagnetisation (Extended)
- Apply the right-hand grip rule to find solenoid polarity (Extended)

## Core: Properties of Magnets & Magnetic Materials

**Magnetic Material** — A material that is attracted to a magnet, and can be made into a magnet. Only iron, cobalt, nickel and their alloys (e.g. steel) are magnetic at IGCSE level.

*Example:* Steel is a magnetic alloy of iron and carbon; copper is non-magnetic.

Permanent magnets have two poles: north (N) and south (S). Like poles repel, unlike poles attract. The magnetic force is strongest at the poles, and weakest at the midpoint of a bar magnet.

**Worked example:** A student has two identical steel bars: one is a permanent magnet, the other is unmagnetised. Describe a test to identify which is the magnet, without using any other equipment.

1. Hold one bar stationary, bring one end of the second bar to the middle of the stationary bar.
2. If there is strong attraction, the moving bar is the permanent magnet: the middle of a permanent magnet has no magnetic field, so only the moving magnet will attract the unmagnetised bar.
3. If there is no attraction, the stationary bar is the permanent magnet, as you are holding the unmagnetised bar to the neutral midpoint of the magnet.

> **Exam tip:** Always explicitly state repulsion is the only definitive test for a permanent magnet in written answers, not attraction.

## Core: Magnetic Fields & Field Lines

**Magnetic Field** — The region around a magnet where a magnetic force acts on a magnetic material or another magnet.

*Notation:* Field lines are drawn from north pole to south pole outside the magnet, and south to north inside the magnet.

- Field lines never cross each other
- Closer field lines = stronger magnetic field
- Arrows on field lines point in the direction a free north pole would move

**Worked example:** Draw and describe the magnetic field pattern around a bar magnet, marking the strongest field regions.

1. Draw a bar magnet, label N and S poles on opposite ends.
2. Draw curved lines from the N pole to S pole outside the magnet, getting further apart as you move away from the poles.
3. Mark the regions closest to the N and S poles as the strongest field areas, where field lines are closest together.
4. Add arrows to all lines pointing from N to S outside the magnet.

**Check your understanding**

1. What direction do magnetic field lines point outside a bar magnet?

   *Why:* This matches the direction a free north pole would move if placed in the field.

## Core: Induced Magnetism

**Induced Magnetism** — Temporary magnetism created in a magnetic material when it is placed in a magnetic field. The induced pole closest to the permanent magnet is always the opposite pole, leading to attraction.

*Example:* When an iron nail is held near a permanent magnet, the end of the nail closest to the magnet's N pole becomes an induced S pole, so the nail is attracted to the magnet.

Induced magnetism disappears as soon as the magnetic field is removed for soft magnetic materials (e.g. pure iron). Hard magnetic materials (like steel) retain some magnetism after the field is removed, so can be made into permanent magnets.

**Worked example:** A permanent bar magnet is held touching one end of an unmagnetised steel paper clip. The other end of the paper clip now picks up a second unmagnetised paper clip. Explain why this happens.

1. The permanent magnet induces magnetism in the first paper clip: the end touching the permanent magnet becomes an opposite pole, the far end becomes the same pole as the end of the permanent magnet it is touching.
2. The first paper clip then induces magnetism in the second paper clip, with opposite poles on adjacent ends, leading to attraction between the two paper clips.

## Extended Only: Magnetisation, Demagnetisation & Solenoid Fields

- **Magnetisation methods**: 1. Stroking a magnetic material with one pole of a permanent magnet in a single direction repeatedly; 2. Placing the material inside a solenoid with a large direct current (DC) flowing through it.
- **Demagnetisation methods**: 1. Hammering the magnet repeatedly while facing east-west (away from Earth's magnetic field); 2. Heating the magnet to red hot and cooling while facing east-west; 3. Placing the magnet inside a solenoid carrying alternating current (AC) and slowly pulling it away from the coil.

**Right-Hand Grip Rule for Solenoids** — Used to find the polarity of a solenoid carrying DC current: grip the solenoid with your right hand, so your fingers point in the direction of current flow around the coil. Your outstretched thumb points to the north pole of the solenoid.

**Worked example:** A solenoid has current flowing into the left end of the coil from the top of the windings, and out of the right end of the coil from the bottom. Use the right-hand grip rule to find which end of the solenoid is the north pole.

1. Visualise the current flow: at the left end of the solenoid, current travels clockwise around the coil; at the right end, current travels anticlockwise.
2. Grip the solenoid with your right hand, fingers curling in the direction of current flow (anticlockwise when looking at the right end, clockwise at the left end).
3. Your thumb points to the right, so the right end of the solenoid is the north pole.

> **Exam tip:** The magnetic field inside a solenoid is uniform: draw straight, parallel, evenly spaced field lines along the axis of the coil for exam answers.

## Common pitfalls

- **Wrong:** Claiming attraction is a sure test for a permanent magnet
  - Why it fails: Magnetic materials are attracted to both poles of a magnet, so attraction cannot distinguish between a magnet and an unmagnetised magnetic material.
  - Correct: Only repulsion between two like poles confirms an object is a permanent magnet.
- **Wrong:** Drawing magnetic field lines pointing from south to north outside a magnet
  - Why it fails: Field lines represent the direction a free north pole would move, so they always point away from north poles and towards south poles outside the magnet.
  - Correct: Draw field lines with arrows pointing N→S outside the magnet, and S→N inside the magnet.
- **Wrong:** Classifying aluminium or copper as magnetic materials
  - Why it fails: Only iron, cobalt, nickel and their alloys are magnetic at IGCSE 0625 level; all other metals are non-magnetic.
  - Correct: Memorise the four magnetic materials: iron, cobalt, nickel, steel (alloy of iron).
- **Wrong:** Using the left hand for the solenoid right-hand grip rule (Extended)
  - Why it fails: The left-hand rule is reserved for motor effect calculations later in the syllabus, and will give the wrong polarity for a solenoid.
  - Correct: Only use your right hand for the solenoid grip rule, fingers matching current direction, thumb pointing to the north pole.
- **Wrong:** Stating induced magnetism is permanent
  - Why it fails: Induced magnetism is temporary for soft magnetic materials (e.g. pure iron) and only partially retained in hard magnetic materials (e.g. steel) after the field is removed.
  - Correct: Specify that induced magnetism only exists while the material is inside a magnetic field for pure iron, and fades over time for steel.

## Cheatsheet

| Concept | Core/Extended | Key Fact |
| --- | --- | --- |
| Magnetic materials | Both | Iron, cobalt, nickel, steel only |
| Permanent magnet test | Both | Only repulsion is definitive |
| Field line direction (outside magnet) | Both | North pole → South pole |
| Induced magnet pole | Both | Opposite to the inducing magnet pole |
| Magnetisation methods | Extended | Stroking, or DC current in solenoid |
| Demagnetisation methods | Extended | Hammering, heating, AC current in solenoid |
| Solenoid polarity rule | Extended | Right-hand grip: fingers = current, thumb = north pole |

## What's next

Now you have mastered basic magnetism phenomena, you are ready to progress to more advanced electromagnetism topics in CIE IGCSE Physics 0625 Unit 4. The next concepts build directly on your understanding of magnetic fields and induced magnetism, including the motor effect, electromagnetic induction, and transformers, which make up a large portion of the Electricity and Magnetism unit exam weighting. Be sure to reinforce your knowledge of field line patterns and the right-hand grip rule for solenoids, as these are foundational for all subsequent electromagnetism topics. Practice structured past paper questions to test your application of these rules to exam-style scenarios, and use the cheatsheet for quick last-minute revision before your exams.

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