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You have seen magnetic pulls work across a gap. With an adult, Grace tests six samples: iron, magnetic steel, pure nickel, cobalt, wood, and copper.
Before she tests them, how should Grace check that her magnet works?
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Magnetic Materials
Observe how magnets attract or repel each other and attract some materials and not others
What a learner can do afterwards
- Demonstrate that a classroom magnet attracts iron, nickel, cobalt, and magnetic kinds of steel, but does not make plain wood, plastic, or copper stick
- Show that two magnets can either attract (pull together) or repel (push apart)
- Predict results for at least six named materials, then test and record which objects are attracted
1 · Read
A material is what an object is made of. A classroom magnet pulls strongly on iron, nickel, and cobalt. Many kinds of steel stick too, but some do not. Plain wood, plastic, glass, rubber, wax, copper, and aluminum do not stick in this test. A coin called a nickel may contain a mix of metals. Its name does not mean it is pure nickel.
Each bar magnet has a north pole and a south pole. Different poles pull together: attract. Matching poles push apart: repel. The force can act across a gap. Keep two bars in a line. Hold one still and turn the other end for end. Its facing pole changes, so attraction changes to repulsion, or repulsion to attraction.
With an adult, use a large, covered classroom magnet and safe objects. Keep magnets out of your mouth and nose. Check it on an object known to stick. A working magnet can pull iron while copper does not stick. Bring it near each object, then gently touch it. Check for a pull as you move it away. Record the result. Color and shine cannot replace testing.
Record each object in one of two groups: stuck or did not stick. Count each group. If nine objects were tested and six stuck, three did not stick. To find a missing group, take the known group away from the total. To count objects picked up from two piles, add the piles. Two clips plus three pins make five objects.
An object may feel a pull without sliding. It may be too heavy, or the surface may hold it still. Ask an adult to check for a pull at more than one spot before recording no attraction. Attraction shows magnetic material is present. It does not tell you every material inside. A plastic toy can hide a magnetic steel part.
Use the same object known to stick to check the magnet before and after testing a new object. If the check object no longer sticks, the no-pull result needs another test. Ask an adult to check the magnet. Once the check object sticks again, repeat the new object's test before recording no attraction.
Give each tested object one result. Add the Stuck and Did not stick counts. Compare that total with the number of objects tested. If the totals differ, check for an object counted twice or left out. Keep the result you observed, even when it differs from your prediction.
Test materials with a classroom magnet. Iron, nickel, cobalt, and many steels stick. Different magnet poles attract; matching poles repel. Record each result.
Lesson, questions, worked solutions, and flashcards written for this dataset. Background facts were studied in OpenStax College Physics, University Physics Volume 2, and Physics.
Readings and flashcards written for this dataset. Background facts were studied in OpenStax College Physics, University Physics Volume 2, and Physics.
More to read
Watch the gap
Ask an adult to help you use a large, covered classroom magnet. The adult places an iron clip on a clear table. Move the magnet toward it slowly. Watch for the clip to move while a gap is still there.
That movement shows a pull before touching. Touching is not needed for magnetic attraction to start. Keep magnets out of your mouth and nose. Let the adult handle small test objects.
The material matters
A material is what an object is made of. Iron, nickel, and cobalt respond strongly to a classroom magnet. Many kinds of steel do too, but some steel does not stick.
Plain copper and aluminum do not stick in this test. Shine does not sort these metals for you. A coin's name does not tell you its full mixture of metals either. A coin named a nickel is not necessarily a piece of pure nickel.
Choose the facing ends
Use two labelled bar magnets with an adult. Each bar has a north pole and a south pole. Keep the bars in a line and hold one still. Bring the other near it with north facing south. These different poles pull together.
Turn just the moving bar end for end. Matching poles now face each other and push apart. Changing just one facing pole changes attraction to repulsion. Turning both bars would change both facing poles, so leave one bar still.
Keep a record for each object
Before testing, write or draw one row for each object. Record what you think will happen. Then test it with an adult and add the result. Use two result groups: stuck and did not stick.
Count both groups and check that together they include every tested object. If eight objects were tested and three stuck, five did not stick. A prediction and a result can differ. Keep the result you observed rather than changing it to match your prediction.
A pull without a slide
A magnet makes a magnetic field around it. Through this field, it can pull iron across a gap. It can also pull or push another magnet.
An object may feel a pull without sliding across a table. It may be too heavy, or the surface may hold it still. With an adult, check the magnet on an object known to stick. Then gently touch the test object and check for a pull as the magnet moves away. No slide by itself is not enough to decide that there is no attraction.
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