Electromagnet - Physics Demonstrations - Electromagnet | Physics Undergraduate Labs

The electromagnet coil may become warm with extended use due to resistive heating (I²R losses). Limit continuous operation to 30-60 seconds to prevent overheating. Allow cooling between demonstrations if repeating multiple times.

Purpose

Current through a solenoid with an iron core creates a strong temporary magnet that picks up 20–30 nails. Opening the switch drops nearly all the nails, demonstrating that the magnetization is current-dependent — with one or two remaining due to residual hysteresis in the iron.

Red-wound electromagnet coil with iron core picking up dozens of nails from a plastic bin, connected via red wires through a toggle switch to a 6V Energizer lantern battery

Figure 1: The electromagnet picks up 20–30 nails when the switch is closed. The circuit is simply a 6V lantern battery, toggle switch, and the coil.

Box of Nails

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Safety Warnings

Warning: Electrical Current and Heating

Purpose