What it shows
Plain iron and some kinds of steel are attracted by a magnet, but many stainless steels with nickel are not, or only slightly. By testing kitchen items you learn why steel types differ and how to sort the metals around you.
The science
Iron and its common alloys are ferromagnetic, which means they are strongly attracted to a magnet. Stainless steel with a high amount of chromium and nickel has a crystal structure that is weakly magnetic or non-magnetic. Aluminium, copper and brass are not magnetic at all, even though they conduct electricity.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A small strong magnet
- Steel and aluminium utensils: spoons, plates, tumblers and pressure cooker lid
- Iron tawa or knife, copper and brass items, coins
- A kitchen scale
- A notebook
- A table with columns
Safety
For this project: Never test with items from a pressure cooker that is hot, and an adult must handle sharp knives. Keep the magnet away from phones and cards.
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.
All the safety rulesStep by step
7 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.
Collect 15 metal items from the kitchen and number them.
Predict whether each will be attracted, partly attracted or not, and write down the predictions.
Touch the magnet to each item in several places, such as the base and the handle, and observe.
Score the pull from 0 for none to 3 for a strong pull.
Record the scores in the table and compare with your predictions.
Check items with mixed parts, such as a steel pan with a base of another metal.
Summarise which items are magnetic and what that tells you about their metal.
What you should see
Iron tawa, knives and some cheap steel items pull strongly, while many stainless utensils pull weakly or not at all, and copper, brass and aluminium do not respond at all.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Which metals are magnetic?
Iron, cobalt and nickel, and many steels.
2Why is some stainless steel not magnetic?
Its crystal structure with nickel is not ferromagnetic.
3Is aluminium magnetic?
No.
4Why test several places on a pan?
Different parts may be different metals.
Take it further
Find out why only magnetic pans work on an induction cooker, and test your pans with the magnet.
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.
Free ebooks for this project
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