🧲 P3/P4 · PSLE Topic

Magnets

Magnets explained for PSLE Science. Magnetic materials, poles, magnetic fields, induced magnetism — with Singapore examples and exam tips for P3/P4 students.

📚

Syllabus

P3/P4 · PSLE

⏱️

Reading time

8 minutes

🎯

Exam weight

High — often tested

🧪

Key skill

Apply + explain

💡 Part 1 — Simple explanation

What Is a Magnet?

A magnet is an object that attracts certain metals and can attract or repel other magnets. Every magnet has two ends called poles — a North pole (N) and a South pole (S). The magnetic force is strongest at the poles. Around every magnet is a magnetic field — an invisible region where the magnetic force can be detected. Only certain materials are affected by this field.

🇸🇬 Part 2 — Singapore real-life examples

Magnets in Singapore's Daily Life

MRT card gates use magnetic sensors. The EZ-Link card contains a magnetic chip, and the gantry reader detects the magnetic field change when you tap in.

Recycling centres and junkyards use large electromagnets (magnets powered by electricity) to separate steel and iron scrap from non-magnetic metals like aluminium and copper. One magnet can lift thousands of kilograms of steel scrap in a single lift.

Compass needles — used in orienteering activities at school and by Singapore's scouts and girl guides — always point towards geographic North because Earth's core generates a massive magnetic field, and the compass needle (a small magnet) aligns with it.

Fridge magnets in most Singapore homes hold drawings and notes to the refrigerator because the fridge door is made of steel — a magnetic material.

🔬 Part 3 — Magnetic materials

What Gets Attracted to a Magnet?

Only four elements are strongly magnetic: iron, steel, nickel, and cobalt. Steel is an alloy (mixture) that contains iron, which is why it is magnetic. Everything else — including most other metals — is non-magnetic.

Magnetic	Non-magnetic
Iron, steel, nickel, cobalt	Aluminium, copper, gold, silver, zinc, wood, plastic, glass, rubber, paper

⚠️

Key point — not all metals are magnetic

Aluminium drinks cans, copper wiring, gold and silver jewellery — all metals, all NON-magnetic. Students often assume all metals respond to magnets. Only iron, steel, nickel, and cobalt do.

🔬 Part 4 — Poles and rules

Attraction and Repulsion — The Rules

Like poles repel: N and N push each other apart. S and S push each other apart.
Unlike poles attract: N and S pull each other together.
The force between poles increases as the poles get closer together.
If you break a magnet in half, you do NOT get one N pole and one S pole — you get two smaller magnets, each with its own N and S pole.

💡

You can test whether an object is a magnet or just a magnetic material by seeing if it can REPEL another magnet. A magnetic material (like an unmagnetised iron nail) will always be ATTRACTED to a magnet but can NEVER repel it. Only a magnet can repel another magnet.

🔬 Part 5 — Magnetic fields

The Invisible Field Around Every Magnet

A magnetic field is the region around a magnet where its force can be detected. We represent magnetic fields using field lines:

Field lines run from the North pole to the South pole outside the magnet
Where field lines are closest together, the field is strongest — at the poles
Field lines never cross each other
You can see magnetic field patterns by sprinkling iron filings around a magnet — they align with the field lines

🔬 Part 6 — Induced magnetism

Temporary Magnetism in Magnetic Materials

When a magnetic material (like an iron nail) is placed near or touching a magnet, it temporarily becomes a magnet itself — this is called induced magnetism. The induced magnet's pole closest to the magnet will always be the opposite pole (unlike poles attract), which is why the nail is attracted.

When the magnet is removed, an iron nail loses its magnetism quickly. A steel nail retains some magnetism longer — this is why steel is used for permanent magnets and iron for electromagnets (where you want the magnetism to switch on and off easily).

🔍 Part 7 — The "Why"

Why Do Like Poles Repel?

Magnetic field lines behave like elastic bands under tension — they try to shorten, and they repel other field lines running in the same direction. When two North poles face each other, their field lines both try to run away from N, pushing in the same direction between the poles. They cannot merge, so they push the magnets apart. When N and S face each other, the field lines connect smoothly — N's outward lines are pulled toward S's inward lines, creating attraction.

This repulsion is what makes magnets useful in maglev (magnetic levitation) trains — trains in Japan and China float above the track because like poles on the train and track repel each other, eliminating friction and allowing very high speeds.

🚨 Part 8 — Exam traps

Common Mistakes

❌

Trap 1 — All metals are magnetic

Only iron, steel, nickel, and cobalt. Aluminium, copper, gold, silver — all non-magnetic despite being metals.

❌

Trap 2 — Only magnets can attract magnetic materials

Correct! But remember — an unmagnetised iron bar cannot repel a magnet. It can only attract. Only a magnet can repel another magnet. This is how you tell if something is truly magnetised.

❌

Trap 3 — Breaking a magnet gives separate poles

Breaking a magnet in half gives TWO complete magnets, each with its own N and S pole. You can never isolate a single pole.

📌 Part 9 — Mini summary

Key Points at a Glance

Magnetic materials: iron, steel, nickel, cobalt only. Not all metals are magnetic
Like poles (N-N, S-S) repel. Unlike poles (N-S) attract
Magnetic field: strongest at poles, field lines go N to S outside the magnet
Induced magnetism: temporary magnetism in magnetic materials near a magnet
Only a magnet can repel another magnet — use this to identify true magnets
Breaking a magnet gives two smaller magnets, each with N and S pole

Ready to test yourself? 🧠

You've read the full guide on Magnets — now lock it in with a quiz and flashcards.

🧠 Take the Quiz 📖 Back to PSLE Hub