What is an Electromagnet?
An electromagnet is a temporary magnet made by passing current through a wire that is wrapped around an iron core. If necessary, remind students that an electromagnet differs from other magnets because its magnetism is temporary, occurring only when electric current is passing through the wire. You can turn it on and off with a switch. Electromagnets are a useful tool because you can control them. What are some of the ways to control an electromagnet? You can add and remove coils of wire to change its strength; you can increase or decrease the amount of current flowing in the coils of wire. How can adding coils of wire to an electromagnet change its strength? It increases its strength because the more coils an electromagnet has, the stronger it is. What is the main difference between an electromagnet and a bar magnet? An electromagnet is a temporary magnet; a bar magnet is a permanent magnet; it does not have an off switch. Project electromagnetic transparency and discuss. Ask students
An electromagnet works on the principle that an electric current not only allows electrons to flow in a circuit, but also generates a small magnetic field. When a wire carrying electricity is coiled, the magnetic field becomes even stronger. Iron or steel objects surrounded by this coiled electric wire also become magnetized. This combination of electronic energy, coiled wiring and conductive metal object forms the basis of an electromagnet. That’s the nickel tour version of how an electromagnet is formed. Here’s the real science behind an electromagnet: It may be easier to think of an electromagnet as an ELECTRON magnet, not an ELECTRIC magnet. What we’re really dealing with here is the free flow of electrons in a circuit and their effects on the wire carrying them. To recreate the basic principles of an electromagnet, you will need a supply of bare copper wiring (available at local hardware stores), a D-size chemical battery and an iron or steel nail. The reaction between the metals
An electromagnet is simply a coil of wire. It is usually wound around an iron core. However, it could be wound around an air core, in which case it is called a solenoid. When connected to a DC voltage or current source, the electromagnet becomes energized, creating a magnetic field just like a permanent magnet. The magnetic flux density is proportional to the magnitude of the current flowing in the wire of the electromagnet. The polarity of the electromagnet is determined by the direction the current. The north pole of the electromagnet is determined by using your right hand. Wrap your fingers around the coil in the same direction as the current is flowing (conventional current flows from + to -). The direction your thumb is pointing is the direction of the magnetic field, so north would come out of the electromagnet in the direction of your thumb. DC electromagnets are principally used to pick up or hold objects. When connected to an AC voltage or current source, the electromagnet wil
