Magnetism

by

Shirley Cesair


This lesson is designed to help third grade students learn about magnets and magnetism.

Objective:

The students will make an electromagnet and determine the strength of the electromagnet.

Strategy:

Activity 1

Students will work in pairs. Each pair of students will receive a baggie containing materials needed. Allow the students ten or fifteen minutes to explore and manipulate the materials. Have one student from each group connect their compass with wire through the holes in the cardboard. Insert the wire through the Fahnestock clips on both ends. Place the wire over the compass. What happens and why?

Concept:

The electrical current flowing through a wire will create a magnetic field. This magnetic field causes the needle to turn at a right angle to the wire. Reverse the connections to the battery, thus reversing the direction of the current flow, and the needle will point in the opposite direction.

Activity 2

Using the same bag of materials, the pairs of students will begin wrapping the wire around the nail in the same direction until a foot of wire is left at both ends. Insert the end wires into the Fahnstock clips. Hold the electromagnet over a small pile of paper clips, tacks or other small metal objects. How many objects does your electromagnet attract? Take the wire off the battery terminal, and the tacks will immediately fall off.

Concept:

The current passing through the wire produces an invisible magnetic field. When the current is cut off, the magnetic field disappears, then the molecules of the iron return to their helter-skelter position and the nail loses most, but not all, of its magnetism.

Performance Assessment:

As a result of the electromagnet mini-teach, the sixth grade students will be able to describe the characteristics of a magnet and an electromagnet. Both attract metal and have magnetic fields; the electromagnet needs an electrical current.

The students will be able to make an electromagnet with a wire, a battery, and a nail.

The students will be able to test the strength of the electromagnet by using more coiled wire and additional batteries and nails.

Conclusions:

In activity 1 we found that electricity can produce magnetism and magnetism can produce electricity. The opposite ends or poles of magnets are attracted to each other and like ends repel.

In activity 2 we found that current through a wire produces an invisible magnetic field. When the current is cut off, the magnetic field disappears, then the molecules of the iron return to their helter-skelter position and the piece loses most, but not all, of its magnetism.

References:

Students discover with their hands. The student in the picture below enjoyed seeing the patterns in the magnetic field in the iron filings.

Iron filings can usually be purchased or ordered at your local teacher supply store. You can make a bottle last for a long time with a little thrift. Teach the students to keep a file folder under the filings at all times. When they are finished playing they can use the folder to pour the filings back into the bottle.

If a student raises the folder with filings on it then they can put the magnet underneath to see patterns of magnetic force surrounding the magnets and passing through the paper.

Iron filings are a good material to have handy in almost any magnet project.


Back to the SMART index page.