The usual demo to visualize magnetic field lines is to place a paper sheet over a bar magnet and sprinkle iron filings over the sheet. The filings follow the field lines to form the familiar 2D image shown in Fig. 1.
Neodymium magnets are available from Applied Magnets (appliedmagnets.com) and other retailers.
© 2021 American Association of Physics Teachers.
American Association of Physics Teachers