The introduction to this section explains how electromagnets function in telegraphs and telephones. Other magnets inside the motor are attracted or repelled by this magnetic field, causing the coil to spin, which in turn powers the machine. When you push the button on a doorbell, a circuit is completed and current flows through the wires to an electromagnet. This produces a magnetic field which pulls a metal arm against a metal bell to produce the ring. The play mechanism in a tape recorder uses electromagnets.
Audio tape is covered with magnetic particles.
When the magnetic particles on the tape pass through the play mechanism, they produce electronic signals that travel to an amplifier and into a speaker which reproduces the sounds. Objectives demonstrate the connection between electricity and magnetism create an electromagnet experiment with an electromagnet to observe what variables affect the strength and longevity of the magnetic field Procedure Try to use a nail as a magnet to pick up some small metal objects such as paper clips or brads. Take 1.5 meters of insulated wire and strip 2 cm. of insulation from each end. Wrap the wire tightly around a long iron nail leaving 15 cm. Attach the two ends of the wire to the two poles of a battery.