Poles of a magnet; magnetic fields

SPEC 4.7.1.1 / 4.7.1.2 • MAGNETISM & ELECTROMAGNETISM

The opening lesson of Module 7. Poles, fields, and the single most-missed definition in Paper 2: permanent vs induced magnets.

Welcome to Module 7

Magnetism and Electromagnetism is the second-largest module on Paper 2. Five of its eight lessons are Higher Tier only, and many are physics-only — meaning Combined Science students don't cover them.

8

Lessons in Module 7

P2

Examined on Paper 2

5/8

HT-Only Lessons

Why Start Here

Every later lesson — electromagnets, Fleming's left-hand rule, motors, transformers — assumes you can already define permanent vs induced magnets and draw a field correctly. This lesson locks those foundations down.

Poles & the Like/Unlike Rule

Every magnet has two poles — points where the magnetic force is strongest. They are labelled N and S. Strictly these stand for north-seeking and south-seeking — because a freely-hanging magnet's "N pole" is the end that seeks (points toward) geographic north. The behaviour between two magnets follows one rule.

The Rule

Like poles repel. Unlike poles attract.

N repels N · S repels S · N attracts S

Spec Wording — Non-Contact Force

The attraction and repulsion between two magnetic poles are examples of a non-contact force — the magnets exert a force on each other without touching. Sits alongside gravity and electrostatic force as the three non-contact forces you need to know.

Memory Hook

Magnetic poles follow the same rule as electric charges: like repels like, opposites attract. Force always acts along the line joining the two poles.

Permanent Magnets

A permanent magnet produces its own magnetic field — always. Whether or not any other magnet is nearby, the field is there.

Permanent Magnet

A magnet that produces its own magnetic field, even when no other magnet is near.

What Makes a Permanent Magnet

Only a small group of materials can hold permanent magnetism. The four magnetic elements are:

Iron

Steel (an iron alloy — retains magnetism better than pure iron)

Nickel

Cobalt

Plus certain alloys of these (e.g. alnico). Most metals — copper, aluminium, gold — are not magnetic.

Watch The Wording

"All metals are magnetic" is a common GCSE error. Only those four elements (and their alloys) are. Most metals you can think of are non-magnetic.

Induced Magnets

An induced magnet only becomes magnetic because another magnet is nearby. Take the other magnet away — the magnetism is gone.

Induced Magnet — Mark-Scheme Definition

A material that becomes a magnet when placed in a magnetic field.

Or equivalently: a material that loses most/all of its magnetism when removed from a magnetic field.

How Induction Works

Bring a permanent magnet close to a piece of iron. The iron is now in the magnet's field. Atoms inside the iron align with that field — the iron becomes a magnet itself. Pull the permanent magnet away, the alignment breaks down, the iron stops being a magnet.

Force Direction — Always Attractive

The force between a permanent magnet and an induced magnet is always attractive. The induced magnet's atoms align so that the face nearest the permanent magnet's N pole becomes S (and vice versa) — unlike poles, so the force attracts. Induced magnets never repel.

Permanent vs Induced — Side by Side

The exam tests the distinction directly. Know both columns.

PropertyPermanent MagnetInduced Magnet

Has its own field?Yes — alwaysOnly while in another magnet's field

What happens when removed from the other magnet?Unchanged — field staysLoses most or all of its magnetism

Force between it and a permanent magnetCan attract or repel (depending on poles)Always attractive

Example materialHardened steel, alnico alloySoft iron, an iron paperclip

The Repulsion Test

Hold a metal bar next to a known permanent magnet. If it repels in any orientation, the bar must be a permanent magnet. If it only ever attracts, it is either an induced magnet or unmagnetised magnetic material — never a permanent magnet. Repulsion is the only way to prove a bar is a permanent magnet.

Examiner Alert — Induced Magnets

The single most-missed definition mark in Module 7. From the official examiner report:

"51% of students knew what an induced magnet is. Responses sometimes confused magnets and magnetic materials." AQA Examiner Report — Paper 2H, June 2023, Q04.3

Critical — From The Mark Scheme

The Jun 2023 mark scheme is explicit: "'temporary magnet' alone is insufficient". Calling an induced magnet "temporary" does not score the mark. You must describe the mechanism.

Weak (0 marks)

"An induced magnet is a temporary magnet."

Why it fails: the word "temporary" describes the effect, not the cause. The mark scheme rejects it.

Strong (1 mark)

"An induced magnet is a material that becomes a magnet when placed in a magnetic field, and loses its magnetism when removed."

Why it scores: describes the cause (placing in a field) and the loss (removed from the field).

What is a Magnetic Field?

The space around a magnet is different from the space far away — a compass placed near a magnet swings to align with something invisible. That something is the magnetic field.

Magnetic Field

The region around a magnet (or a current-carrying wire) where another magnet — or a magnetic material — would experience a force.

Field Direction — Spec Wording

The direction of the magnetic field at any point is the direction of the force that would act on another north(seeking) pole placed at that point. A compass needle's N end aligns with this direction — which is why we use a compass to map a field.

Strength Depends on Distance

The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles and gets weaker the further away you go. We show this on a diagram by drawing field lines closer together where the field is stronger.

Field Lines of a Bar Magnet

The classic field — symmetrical, looping from N to S outside the magnet.

What To Notice

Arrows always come out of N and into S on the outside of the magnet.

Lines are closer together near the poles — that's where the field is strongest.

Further from the magnet, lines spread out — the field gets weaker.

Three Rules for Drawing Field Lines

Three things examiners look for on any drawn field. Get all three correct and the marks follow.

Rule 1 — Direction

Outside the magnet, field lines run from N to S. Always include arrowheads. A field-line drawing without arrows scores zero for direction.

Rule 2 — Never Cross

Field lines never cross each other. At any point the field has one direction — and a single point can't have two arrows pointing different ways.

Rule 3 — Spacing = Strength

The closer the lines, the stronger the field. So lines cluster near the poles and spread out further away. Don't draw evenly-spaced parallel lines around a bar magnet.

Common Drawing Errors

Forgetting arrowheads · drawing arrows S to N outside · crossing lines · drawing too few lines (always draw at least 4–6 on each side).

Earth's Magnetic Field

Earth itself behaves like a giant bar magnet. The field is generated by movement of molten iron in the outer core.

The Confusion You Must Survive

The compass N end points toward the geographic North. Unlike poles attract — so the magnetic pole near geographic north must actually be a magnetic South pole. Geographic north pole = magnetic south pole.

Spec Skill — Evidence That Earth's Core is Magnetic

A compass needle always aligns with Earth's field — anywhere on the planet. Three observations point to a magnetic core:

The compass behaves as if a giant bar magnet sat inside the Earth — so Earth must have a magnetic field of its own.

The field is too strong and global to come from surface rocks alone — it must originate deep inside the Earth.

The core is known to contain molten iron; movement of this liquid iron generates the field — which is why the core must be magnetic.

Using a Plotting Compass

A magnetic compass contains a small bar magnet on a pivot. Drop a plotting compass onto a piece of paper next to a bar magnet — the needle rotates to align with the field at that point.

Method To Map A Field

Place the bar magnet flat on paper and trace around it.

Put a plotting compass near one pole. Mark a dot at each end of the needle.

Move the compass so its tail sits on the previous head-dot. Mark the new head.

Repeat until you've traced a smooth curve from N to S. Then start a new line.

Magnetic Materials — The Short List

Examiners often slip in distractors like "copper" or "aluminium" as candidate magnetic materials. They are not magnetic. Learn the list.

Magnetic

Iron

Steel (iron alloy)

Nickel

Cobalt

Alloys of these (e.g. alnico)

Not Magnetic

Copper

Aluminium

Gold, silver, brass

Lead, tin, zinc

Plastics, wood, glass

Soft Iron vs Hardened Steel

Soft iron magnetises and demagnetises easily — perfect for induced magnets and electromagnet cores. Hardened steel retains its magnetism — perfect for permanent magnets. Same family, different jobs.

Practice Question 1

A student has two identical-looking iron bars. One is a permanent magnet, the other is just a piece of unmagnetised iron. The student also has a third bar that is a known permanent magnet.

Describe a method the student could use to identify which iron bar is the permanent magnet, and explain how they would know.3 marks

P

Bring each iron bar in turn close to the known permanent magnet, testing both ends.

E

Only a permanent magnet can repel another permanent magnet; an unmagnetised iron bar is only ever induced and so will only ever attract.

E

If a bar repels the known magnet when turned to one orientation, that bar is the permanent magnet. The bar that only attracts (in every orientation) is the unmagnetised iron.

Practice Question 2

Define what is meant by an "induced magnet". Your answer should make clear how an induced magnet differs from a permanent magnet.2 marks

P

An induced magnet is a material that becomes a magnet when placed in a magnetic field.

E

It loses most or all of its magnetism when removed from that field.

E

In contrast, a permanent magnet produces its own magnetic field — it keeps that field even when no other magnet is nearby.

Mark scheme note: answers that only say "an induced magnet is temporary" do not score. The mechanism (becomes / loses when placed / removed) is what earns the mark.

Common Errors to Avoid

Three high-frequency mistakes flagged in examiner reports across recent years.

Students Often WriteCorrect VersionWhy It Matters

"All metals are magnetic"Only iron, steel, nickel, cobalt and certain alloys are magneticFundamental property — most metals are not magnetic

Field lines drawn from S to N outside the magnet, or without arrowsField lines run from N to S outside the magnet, with clear arrowheadsConvention — direction-of-field mark is lost otherwise

"An induced magnet is a temporary magnet""A material that becomes a magnet when placed in a magnetic field (and loses its magnetism when removed)"Mark scheme explicitly rules out "temporary" alone

Checkpoint

You should now be able to do all of the following without prompting.

You Can Now

State the like/unlike rule — like poles repel, unlike poles attract

List magnetic materials — iron, steel, nickel, cobalt and their alloys

Define a permanent magnet — produces its own field at all times

Define an induced magnet to mark-scheme standard — becomes a magnet when placed in a field; loses magnetism when removed

Define a magnetic field — region where another magnet or magnetic material experiences a force

Draw the field around a bar magnet — arrows N to S outside, lines never cross, denser near the poles

Explain Earth's magnetic field — and the trick that geographic N is magnetic S

Use a plotting compass to map a magnetic field

Coming Next — 7.02

Electromagnetism. Currents create magnetic fields. We'll cover the right-hand grip rule, solenoids, and electromagnets — the foundation for everything from Fleming's left-hand rule to transformers.