Magnets and electromagnets

Integrated ScienceElectricity & MagnetismAges 12–13

Compare the magnetic field of a permanent bar magnet with the field of a current-carrying coil (an electromagnet). On the Bar magnet screen, change the strength, flip the poles and use a compass and a field meter to explore the field around the magnet. On the Electromagnet screen, the heart of the simulation, students change the number of turns, the DC supply voltage (reverse its sign to swap the poles) or switch to an AC supply (set the amplitude and frequency), and add or remove an iron core to see the field get stronger, keep reversing with alternating current, or disappear when the current is switched off – the key difference from a permanent magnet, and the reason electromagnets are used in electromagnetic cranes, electric bells and relays. Based on the "Magnets and Electromagnets" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Electromagnets and their uses