Magnetism – Learning Outcomes Discuss the nature of magnets, particularly with reference to poles. Demonstrate the properties of magnets. Demonstrate and discuss the magnetic effect of electric current. Discuss the uses of electromagnets.

Nature of Magnets Magnets will attract ferromagnetic materials – iron, nickel, cobalt, and some alloys of these. Magnetic forces are strongest at the ends, called poles. Magnets always have two poles – north and south. Cutting a magnet creates new poles at the cutting point. If allowed to rotate freely, a magnet will line up north- south. Like poles repel and unlike poles attract. Magnets can induce magnetism in ferromagnetic materials.

Magnetic Effect of an Electric Current Align a wire with a compass needle. Connect the wire to a power supply and note a deflection in the compass needle. Reverse the direction of current and note that the compass needle deflects in the other direction. Turn off the current and note no deflection in the compass needle. The compass needle is only deflected when a current flows in the wire. Thus, current-carrying conductors cause a magnetic field.

Magnetic Effect of an Electric Current

Electromagnetism We call this effect electromagnetism. When a current-carrying wire is wrapped around a soft iron core, the combination is called an electromagnet. They are used in: electric motors, electromagnetic relays, scrap yards on cranes.