ELECTROMAGNETS4.6C Demonstrate that electricity travels in a closed path creating an electrical circuit and explore an electromagnetic field.

Building an Electromagnet

I was thinking about a big old junkyard crane that I once saw. The crane used a big magnet to lift cars and put them on train cars. The crane operator could turn the magnet on and off!

Could you make a model junkyard magnet that turns on and off?

Magnetic Interactions

Let’s review magnetic interactions. 1st let’s pour these small washers into one of the wells on a circuit base. Then we’ll use a magnet, a steel rivet, and the washers to demonstrate. After each discuss.

a. Use a doughnut-shaped permanent magnet to pick up the washers and move them to the opposite well. You can’t turn off!

b. Use the magnet to pick up the rivet. The rivet sticks because it’s steel.

c. Use the rivet stuck to the magnet to pick up the washers. Magnetism is induced in the rivet by the magnet, and you can’t turn it off without removing the magnet.

d. Try to use the rivet by itself to pick up the washers.

No washers stick to it because it’s not a magnet!

Let’s Explore!

We know that a magnetic field surrounds a magnet, but I wonder if there are other magnetic fields. What could you use to detect a magnetic field? What about a compass?

***Any movement from the compass means it detects a magnetic field.

How can you turn a steel rivet into a magnet that turns on and off?

Electromagnets

This is a steel rivet, but it isn’t a magnet.

Groups come get: 1 Rivet1 Wire1 Circuit Base1 Switch1 cup of small washers

Design Electromagnets:

You will work with your small group to create a model junkyard that turns on and off.

Let’s Share!

How did you make a magnet that could turn on and off?

• The wire must be wrapped around the rivet the same # of winds. • Wind the wire between the 1st rubber washer and the head of the rivet. • The wire must be in a circuit with a switch and a D-Cell.• Pick up the washers on the head of the rivet.• The rivet is a magnet only while the circuit is closed.

What can you do to make it stronger and pick up more washers?

Let’s Draw and Label

Draw your electromagnet. (Make sure you draw it big enough to label.)

Electromagnet: is a magnet made using the flow of electricity through an insulated wire to produce a magnetic field. The magnetic field is stronger when you wrap the wire around a piece of iron or steel, which becomes a temporary magnet. We call the piece of iron/steel the

core. The wrapped wire is called the coil.

Label the components on the drawing and tell the function of each:The Switch, wire, steel rivet, and the D-Cell