Magnetism

by Sally M. Walker

photographs by Andy King

2006

Ages: Grades 2-5

Genre(s): Informational

Summary: This book describes what magnets are and how they work.  Explaining details of how the atoms work to make the magnetic force and how the magnet comes to have two poles, north and south.  The author also describes why some materials are attracted to magnets and how some can become temporary magnets.  The book also includes activities to help students experiences magnets.

My reaction:  I found this book very interesting.  I learned a lot about magnets that I either never knew or had long forgotten.  The format is very simple so elementary children can understand the concepts.

Activity: (Home Science Tools Website)

Magnetic Propulsion

A maglev (magnetically levitated) train doesn't use a regular engine like a normal train. Instead, electromagnets in the track produce a magnetic force that pushes the train from behind and pulls it from the front. You can get an idea of how it works using some permanent magnets and a toy car.

What You Need:

• toy car
• 3 bar magnets

What You Do:

1. Tape a bar magnet to small toy car with the north pole at the back of the car and the south pole at the front.

2. Put the car on a hard surface, like a linoleum floor or a table. Hold a bar magnet behind the car with the south pole facing the car. As you move it near the car, what happens? The south pole of your magnet repels the north pole of the magnet on the car, making the car move forward.

3. Have someone else hold another magnet in front of the car, with the north pole facing the car. Does the car move faster with one magnet 'pushing' from behind and the other magnet 'pulling' from ahead?

In our example, the permanent magnets have to move with the car to keep it going. In a maglev track, though, the electromagnets just change their poles by changing the direction of the electric current. They stay in the same spot, but their poles change as the train goes by so it will always be repelled from the electromagnets behind it and attracted by the electromagnets in front of it!