Magnets and magnetic fields
How does a compass always know which way is north?
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Explain
Magnets pull on some metals.
They can push or pull each other.
A magnet has a north pole and a south pole. Opposite poles attract, and the same poles repel.
Around every magnet is an invisible magnetic field. Tiny compasses show which way it points.
The Earth is like a giant magnet, and that is why a compass works.
Magnetic field lines go from north poles to south poles outside a magnet. They are closest where the field is strongest.
Iron, nickel and cobalt are the common magnetic metals. Each compass needle is a small magnet, which lines up with the field.
Magnetic poles always come in pairs. Cut a magnet in half, and you have two smaller magnets.
- A magnet has two poles
- A field surrounds it
- Compasses line up
Want the full story?
Earth's field comes from moving molten iron deep inside. Its magnetic pole in the north is really a south-seeking pole, which is why it attracts the north end of a compass. The field also slowly shifts over time.
Try it at home
Ask a grown-up to help
You need a fridge magnet, paper clips, some household objects.
You need: a fridge magnet, paper clips, some household objects.
Find things that a magnet sticks to.
- Guess which objects a magnet will pull.
- Test each one.
- Try pulling a paper clip through paper.
What's happening: magnets attract iron and steel, and the field passes through paper.
Keep magnets away from phones and bank cards, and never let small children swallow them.
Physics is life
Your body
Hospitals use giant magnets to see inside you.
Daily life
Fridge magnets stick on doors.
Nature
Birds may sense magnetism.
Space
Earth has a magnetic shield.
Quick check
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Words to know
Magnet: An object that attracts iron and has north and south poles.
- Magnet
- An object that attracts iron and has north and south poles.
- Magnetic field
- The area around a magnet where its force can be felt.
- Force
- A push or a pull on something.