Electromagnets ~30 Minutes

NOTE: The wires tend to get hot if the magnet is 'on' for extended periods of time. Tell students to on have the magnet connected to the batteries when they are using it.


BC Science Content:

-electromagnetism (Grade 7)

electromagnetismMaterials: about 2m of insulated wire (the thinner the better), large steel bolt or nail, two Dcell batteries, about 20 loose paperclips.

Doing it:
A1. Wind the wire tightly around the nail or bolt from end to end. Leave about 20cm of wire off the nail or bolt at each end.
A2. Place the magnet in a pile of the paperclips. Tape the wires to the terminals of a battery and lift the magnet. How many paperclips does it pick up?

A3. Now tape two Dcell batteries together in series, and repeat A2.

Fig 1.1 - Electromagnet from B1-B2.

B1. You will now wind a second layer of wire around the nail or bolt. Connect the new wire to one of the leads coming of the magnet, and then tightly wrap another level or wire around it. Leave about 20cm at the end like in A1. B2. Now repeat A2, using first the double battery from A3, and then with a single battery. B3. Do more batteries allow more clips to be picked up? Do more windings allow more clips to be picked up?

Fig 1.2 - Doubly wrapped electromagnet powered by 2 Dcells picking up paperclips


A wire carrying a current will produce a magnetic field around it. When you wrap the nail in wire two things happen: Because each loop around the nail is in the same direction, the field produced by each of them will be in the same direction and create one large field. This field also penetrates the nail...