Building an Electromagnet Investigation 4: current attractions Day 2

How can energy be transferred from one material to another? Science Essential Question

What happens to a material when energy is transferred to it? Science Essential Question

Challenge: Materials Needed for the Challenge: Rivet Electromagnet wire Short wire Circuit Base D-cell Switch Cup of small washers There is a new longer wire today for each group. The long wire may be useful for making your rivet into a magnet that turns on and off. Using these materials, how will you make a magnet that can turn on and off?

An Electromagnet Demonstration Click the title above to see the demonstration.

How did you make a magnet that could turn on and off? Sharing Your Designs How did you make a magnet that could turn on and off? Did you notice… The wire must be wrapped around the rivet. The wire must be in a circuit with a switch and a D-cell. The rivet is a magnet only while the circuit is closed.

Electromagnet You discovered the electromagnet. An electromagnet is a piece of iron with insulated wire wrapped around it. While electric current is flowing through the wire, the piece of steel becomes a temporary magnet.

Finding the Best Electromagnet Design I noticed that just about everyone wound the wire around their rivets in a different way. Work in your group to find the best location to wrap the wire on the rivet to make the rounded head of the electromagnet as strong as possible. Each group will share their results with the class.

Setting Standards for the Investigation In order to compare results of our investigation, we will need to set some standards for the investigation. Always use the same number of winds – 30 to 40 works best. What number should we choose? Pick up the washers on the head of the rivet. Count the washers lifted to determine the strength of the magnet.

Sharing Your Results How did your group wrap the wire to produce the strongest magnet? To Summarize: Q: How can you make a magnet that turns on and off? A: A magnet can be made by wrapping insulated wire around a steel rivet (iron core) and connecting it to an electric circuit. Q: What placement of the wire on the rivet makes the strongest electromagnet? A: The best design is to wrap the wire tightly between the head of the rivet and the first washer.

Vocabulary You Should Know: An electromagnet is a coil of wire, usually wound around a core of iron or steel, which produces a magnetic field when electricity flows through the wire. The core is the material around which a coil is wound. A coil is wire wound repeatedly around a central core.

Something to think about…. How else can you change the strength of an electromagnet? Homework: Read the article Magnetic Attraction and answer the questions.