GoalName magnetic materials and the properties of a magnet’s poles, and explain why a magnet always has two poles.
New words
magnet · an object that attracts iron and some other materialsmagnetic material · a material attracted by a magnet: iron, steel, nickel or cobaltpole · the end of a magnet where the force is strongestcompass · a freely turning magnetic needle in a case that is not magnetic
Explanation
An old Greek story says that lodestone, a natural magnetic rock, was found in a place called Magnesia. Magnets come in many shapes: bar, U-shaped, horseshoe, cylinder and needle. A magnet attracts iron, steel, nickel and cobalt, which are magnetic materials. It does not attract copper, aluminium, gold, silver, wood, plastic or glass. So it is wrong to say that a magnet attracts all metals. The magnetic force is strongest at the poles. A bar magnet that hangs freely settles in the north–south direction, and its north-seeking end is called the north pole (N). Earth itself acts like a giant magnet, which is why a compass needle, a small freely turning magnet, can show direction. If you break a magnet, each piece is a smaller magnet with its own two poles: a single pole alone does not exist. Keep strong magnets away from phones, bank cards and people who have a pacemaker.
Attracted by a magnet
Not attracted
iron nail
copper wire
steel paper clip
aluminium foil
nickel
wood, plastic, glass
Worked examples
With a small fridge magnet, Fatma tests a nail, a paper clip, a plastic comb, a wooden spoon, aluminium foil and a copper wire. She writes only what happens. The nail and the clip are pulled and the others are not. Not every steel object is pulled, so she describes each result and does not guess.
A bar magnet hangs from a thread and slowly turns until one end points north. That end is the north pole N. The other end points south and is the south pole S. This works because Earth acts like a giant magnet.
A bar magnet is broken into two. Each piece has an N pole and an S pole, so two smaller magnets are formed. You cannot get a piece with one pole only.
Class activity
Magnet tests, with an adult. With a small fridge magnet, test ten things at home. Make a table and write only what you see happen, for example “pulled to the magnet” or “nothing happened”. Hang a bar magnet from a thread to see which way it settles, or put a compass beside it. Keep magnets away from phones, cards and screens. Never use strong magnets.
Practice
1
Name three magnetic materials.
For example iron, steel, nickel or cobalt.
2
Does a magnet attract all metals? Explain.
No. It does not attract copper, aluminium, gold or silver.
3
A bar magnet is broken in half. How many poles does each half have?
Two: each half is a smaller magnet.
4
What is a compass needle?
A small magnet that turns freely and settles north–south.
