Investigation 17B

1. Key Question: How are electricity and magnetism related? Investigation 17B Electromagnets

2. 17.2 Electomagnets • Electromagnets are magnets that are created when there is electric current flowing in a wire. • The simplest electromagnet uses a coil of wire wrapped around some iron.

3. 17.2 Right hand rule • To find the north pole of an electromagnet, use the right hand rule. • When the fingers of your right hand curl in the direction of the wire, your thumb points toward the magnet’s north pole.

4. 17.2 Electromagnets in Appliances • By changing the amount of current, you can easily change the strength of an electromagnet or even turn its magnetism on and off.

5. 17.2 Building an electromagnet • You can easily build an electromagnet from wire and a piece of iron, such as a nail. • Wrap the wire in many turns around the nail and connect a battery.

6. 17.2 Building an electromagnet • There are two ways to increase the current in a simple electromagnet: • Apply more voltage by adding a second battery. • Add more turns of wire around the nail.

7. 17.2 Similarities in permanent and electromagnets • The charged electrons in atoms behave like small loops of current. • Electric current through loops of wire creates an electromagnet. • Atomic-scale electric currents create a permanent magnet.

8. 17.2 Magnetic materials • Atoms act like tiny magnets. Permanent magnets have their atoms aligned, creating the magnetic forces we observe.

9. 17.2 Magnetic materials • In iron, the atoms are free to rotate and easily align their individual north and south poles.

10. 17.2 Nonmagnetic materials • The atoms in non-magnetic materials, like plastic, are not free to move or change their magnetic orientation.