4.3Unit 9: Magnetism and electromagnets

Electromagnets — Cambridge Checkpoint Physics 0893 Revision Notes & Topical Questions

5 min read 9 parts Lesson 3 of 4 2 quizzes

📚 Cambridge Checkpoint Physics 0893 Hub / Topical Revision

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Lesson summary

4.3 Electromagnets — CHECKPOINT PHYSICS 0893 notes: Describe how to make an electromagnet, how its poles work and where electromagnets are used.Magnetic = attracted to a magnetMagnetic metals — iron, nickel, cobalt and steelSteel — a mixture containing a large proportion of ironN…

Non-magnetic metals
Magnetised
Switching off
Finding the poles
Reversing the poles
On and off

Part 1 of 7Magnetic materials

Magnetic

Magnetic attracted to a magnet

Magnetic metals

Magnetic metals iron, nickel, cobalt and steel

Steel

Steel a mixture containing a large proportion of iron

Non-magnetic metals

Non-magnetic metals copper, aluminium and zinc

Magnetised

Magnetised turned into a magnet

Part 2 of 7Permanent magnets and electromagnets

	Permanent magnet	Electromagnet
Magnetic field	Always there	Only while current flows
Switching	Cannot be switched off	Can be switched on and off
How made	Magnetising a magnetic material	Current through a coil around a magnetic core
Strength	Fixed	Can be varied

Part 3 of 7Making an electromagnet

Wrap insulated wire tightly around an iron nail to make a coil.

Leave enough wire at each end to connect to a cell.

Make sure only the plastic coating touches the nail.

Connect the coil in a circuit with a cell and a switch.

Close the switch and test the pointed end with paperclips.

Switch off after a short time, because the cell will not last long.

Part 4 of 7Parts of an electromagnet

Parts of an electromagnet

Coil

Coil the wire wrapped around the core

Core

Core the magnetic material in the middle of the coil

Current

Current when current passes the core becomes magnetised

Switching off

Switching off the core loses most of its magnetism

Part 5 of 7Poles of an electromagnet

Two poles

Two poles an electromagnet has two poles like a bar magnet

Finding the poles

Finding the poles use a compass or bring a bar magnet with known poles near and see which end attracts or repels

Reversing the poles

Reversing the poles wrap the coil in the opposite direction or reverse the connections to the cell

Part 6 of 7Applications of electromagnets

Application	How the electromagnet is used
Fire door	Holds the door open and releases it when the alarm switches the magnet off
MRI scanner	A powerful electromagnet produces images inside the body
Scrapyard	Lifts iron and steel and drops them when switched off
Toaster	Holds the basket down until a timer switches it off and the toast pops up
Electric bell	Pulls the hammer to the bell and releases it repeatedly
Electric motor	Changes electrical energy into kinetic energy

Part 7 of 7Why electromagnets are useful

On and off

On and off the magnet can be switched on and off where a permanent magnet could not

Control

Control the strength of the field can be changed

Sorting

Sorting only magnetic metals are lifted from scrap, leaving metals such as copper, aluminium and zinc behind

Key terms

Term	Meaning
Electromagnet	Magnet made by current through a coil around a magnetic core.
Coil	Wire wrapped around a core.
Core	Magnetic material in the middle of a coil.
Permanent magnet	Magnet whose field is always there.
Magnetised	Turned into a magnet.
Magnetic material	Material attracted to a magnet.

Avoid these mistakes

Mixing up magnetic and magnetised — magnetic means attracted to a magnet and magnetised means turned into a magnet.

Thinking an electromagnet keeps its field when switched off — it loses most of its magnetism.

Thinking all metals can be used as the core — only magnetic metals work.

Letting bare wire touch the core in the coil — only the plastic coating should touch.

Last updated: 12 October 2026