What it shows
Every magnet has two poles. Unlike poles pull together and like poles push apart, and we can use the push to move a small car without touching it.
The science
A magnet has a north pole and a south pole. Two different poles pull each other, and two same poles push each other away. This push and pull acts across a small gap without touching. When we tape a magnet to a car, bringing a same pole near makes the car roll away.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Two small bar magnets (free from old toys or a magnet set)
- Two cardboard boxes, matchbox size
- Four bottle caps and two straws or skewers per car, for wheels and axles (free)
- Sticky tape
- A smooth table or a long tray
- Red and blue marker
Safety
For this project: An adult must help tape the magnets and keep them away from phones and watches. Keep small magnets away from young children.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
Step by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Bring the two magnets end to end: the two ends that push apart are the same pole. Colour those two ends red and the other ends blue.
Stick the magnet on the top of each matchbox with tape, with the red end at the front.
For wheels, push two straws or skewers through each box as axles and fix a bottle cap on each end so they spin freely, or just slide each box on a smooth tray.
Place the two cars on the table with their fronts facing each other and the red ends close.
Slowly push one car towards the other and watch the second car move away without touching.
Turn one car round so red meets blue and watch the cars pull together.
Write down what you see for same poles and different poles.
Draw the two cars with arrows showing the push and the pull.
What you should see
Same poles make the cars push apart and different poles pull them together. You can move a car without touching it.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
01How many poles does a magnet have?
Two, a north and a south.
02What happens when same poles meet?
They push each other away.
03What happens when different poles meet?
They pull each other together.
04Does the magnet need to touch the car?
No, the force works across a small gap.
Take it further
Test how far apart the cars can be and still push each other, and draw the distance on a ruler.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
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