An electromagnet consists of an iron core, around which insulated copper wire is wrapped. When a d.c current is passed through the wire, the core becomes magnetic and is able to pick up paperclips. When the current is stopped, the iron core returns to its original non-magnetic state.
Equipment required (per set):
The copper wire needs to be wrapped around the iron nail several times. (25-30 if possible) and then connected to a pair of crocodile clips and to a low voltage power source.
- Large iron nail
- Low voltage power supply (1V)
- PVC coated copper wire
- Crocodile clips
Although the electromagnet could be safely connected to a 1-12V labpack, the wires may melt if too higher current is passed through it. As a result it is probably safer to use a low voltage labpack with an output of around 1V. In any case the electromagnet should only be turned on briefly as it will get hot if left on too long and/or may trip the thermal fuse in the power supply.
Students can measure the strength of the magnetic field created by their electromagnet by seeing how many paperclips it will pick up. These can either be counted or weighed.
Steel nails or steel bars can be used to make an effective electromagnet however it may stay magnetic after the current has stopped flowing. Iron cores will not retain the magnetism.