ELECTRIC MAGNETS

Some magnets, such as bar and horseshoe magnets, are permanent. They have what scientists call "spontaneous permanent magnetism." Their magnetism needs no outside force or energy to create it. A way of making magnetism is by using electricity. When electricity flows through a wire or another similar conducting (carrying) material, it produces a magnetic field around the wire. This is called electromagnetism or EM. In fact, magnetism and electricity are very closely linked. Each can be used to make the other. EM is used in many tools, machines, and devices. Some electromagnetic machines use the electricity from batteries. Others need the much more powerful mains electricity from wall sockets.

The first practical electromagnets were made by the British boot maker and spare-time scientist, William Sturgeon. He used them to amaze audiences at his science shows in the 1820s. The basic design has hardly changed since. You can make a similar electromagnet in the projects.

YOU WILL NEED

Electromagnet:

Wire strippers, 2 yards of wire (insulated, plastic coated, multistrand copper), large iron nail, 9-volt battery, paper clips.


• Adding a switch:
  Hole punch, piece of card, brass fasteners.

STEP 1
Using the wire strippers, carefully remove an inch or two of plastic insulation from each and of the wire. These bare will connect to the battery.

STEP 2
Carefully wrap the wire into a tight coil around the iron nail. The plastic insulation around the wire conducts the electricity around the iron nail.

STEP 3
Connect the wire?s ends to the battery terminals. (It does not matter which is positive or negative.) Test your electromagnet by picking up paper clips.

STEP 1
Make two equal-sized holes in the piece of card. Push the brass fasteners into them. Push one of the fasteners through a paper clip first. Open out the legs of the fasteners.

STEP 2
Connect one end of electromagnet wire to the fastener. Connect the other to a battery terminal. Attach the remaining fastener to the other terminal with short wire. Turn the card over.

STEP 3
Push the paper clip attached to one fastener away from the other fastener. No electricity flows. Turn the clip to touch the fastener. Electricity flows, switching on the electromagnet.