IGCSE 0625 / Section 4.1 / Core

Mapping the invisible.

Scatter iron filings around a bar magnet and a pattern of curves leaps into view. Those curves are a map of where, and how strongly, the magnet can push on another pole. A small compass lets you trace them one arrow at a time.

The key idea

A magnetic field is the region around a magnet where a magnetic force acts. Field lines run from the north pole to the south pole outside the magnet, never cross, and are closest together where the field is strongest, near the poles. A compass needle points along the field line.

Definition · learn the exact words

A magnetic field is the region around a magnet where a magnetic pole experiences a force. Field lines point from the north pole to the south pole outside the magnet, and the closer the lines, the stronger the field.

arrows: north → south (outside the magnet)

A plotting compass needle lines up along the field line, pointing in the direction of the field.

Section 01

Trace the field with a compass.

Move the compass around the magnet and watch the needle line up with the field at each point.

Stage 1 · Learn

Check magnetic fields

Four quick checks. Each correct answer earns XP and lights this skill on your star map.

Quick check+10 XP

Outside a bar magnet, the field lines point...

Quick check+10 XP

Where the field lines are closer together, the field is...

Quick check+10 XP

A plotting compass placed in a magnetic field has its needle...

Quick check+10 XP

A magnetic field is...

Section 02

Reading the pattern.

The spacing of the lines tells you the strength, and the arrows tell you the direction.

Examiner trap

Outside the magnet the arrows on the field lines point from north to south. The lines never cross, and where they crowd together, near the poles, the field is strongest.

Stage 2 · Exam

Exam-style questions

Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.

Finish the four checks above to unlock the exam questions
Exam style+20 XP

The magnetic field of a bar magnet is strongest...

Exam style+20 XP

Field lines around a magnet are drawn and one pair is shown crossing. This must be wrong because field lines...

Exam style+20 XP

A compass is placed just off the north pole of a bar magnet. Its needle points...

Skill unlocked

Magnetic fields, mastered.

Magnetic fields are mapped. Keep the chain going.

-Rank -Level -Score -Topics
Go deeper · practice
Six original Cambridge-style questions
The magnetic field as a region of force, field line direction and spacing, and the plotting compass. Attempt each, then reveal the worked solution.
Stage 3 · master the unit
Electricity and magnetism challenge
Mixed questions across the whole unit, each one worth XP. Start this only when you feel confident across every topic in the unit, not just magnetic fields.
Start the unit challenge →