Magnetic field of bar, U-shaped, and electromagnet magnets

Integrated ScienceElectricity & MagnetismAges 12–13

Iron filings scattered on a card arrange themselves into a magnetic field pattern around the magnet; a compass needle placed in the field turns to follow the field lines. Students drag the magnet through the filings, tap an empty spot to place another compass, and press Flip poles to watch the needles swing around. For the electromagnet: drag the current slider, change the number of coil turns, switch off the current to make the field disappear, and reverse the current to swap the poles.