Although we cannot see magnetic field lines, we can detect them using iron filings. The tiny pieces of iron line up in a magnetic field.

Iron fillings reveal a magnet's magnetic field. You can see a magnet's magnetic field by scattering tiny iron filings around it. The iron filings form a pattern that reveals the lines of the ...

A 1/2 inch diameter cylindrical magnet works well. Iron Filings: Available from: Science supply stores like Home Science Tools, Carolina Biological, or Educational Innovations Some craft stores in ...