Activity Instructions - A Magnetometer and Changing Magnetic Fields

Part One

Construct a magnetometer, a tool to detect magnetic fields. We will use the procedure described in the National Center for Atmospheric Research Climate Discovery Teacher’s Guide on Magnetic Sun.

Procedures

1. Lay a pin across the sticky side of a piece of tape.

2. Add a second pin facing the opposite direction. (If the heads of the pins stick out further than the points, the points won’t poke you.)

3. Lay one end of the thread across the pins and tape, oriented perpendicular to the pins.

4. Fold the tape over so that the pins are in the crease. (see figure at left)

Then...

1. Push the thread through the straw.

2. Hold the straw vertically. Adjust the length of the thread so that the taped pins dangle just below the bottom of the straw. Make sure that they do not touch the straw.

3. Fold the free end of the thread over onto the outside of the top of the straw and tape it into place.

4. To magnetize the pins, stroke them (along their length) with a one pole of the magnet.

Then, check to see if the pins point toward the magnet!

Congratulations! You have built a magnetometer. We will use this instrument in the next activity.

Magnetic fields are invisible; we can only see the effects of the magnetic force. Magnetometers are devices used to detect and measure the strength of magnetic fields. Compasses are basically magnetometers with directions marked on them. A magnetometer will dip or point toward a source of magnetism. (You could also have students use their magnetometer to find things in your room or at home that are magnetic, e.g., some pliers).