Day 2: Design and Build a Magnetometer
The students will brainstorm and design an instrument to detect magnetic
field direction. The design will roughly approximate the design included
in this activity.
The students will build a functioning magnetometer, a device for detecting
the relative direction of the local magnetic field.
Opening Probing Question/Quiz (short answer):
Is magnetism a material?
Magnetism seems to be caused by a material and experienced by a material.
We do not yet see consistent evidence that the magnetic field is itself
a material. We can not make a conclusion yet. (And indeed, magnetism is
not a material in the usual sense of the word.)
Ask volunteers to brainstorm methods of detecting a magnetic field
for direction. List responses on board.
Ask student groups to coordinate/refine design suggestions to workable model.
Through discussion, add the following considerations to the student designs:
- Sensitivity of detection;
- Time needed to achieve reliable response;
- Recording data in standardized form to communicate to others.
Discussion goal: Motivate students to think about what it
takes to build a device to measure a physical phenomenon. Ultimately, the
student thoughts ought to foreshadow the construction of the magnetometer.
This can be achieved by providing questions suggesting the need to use a
friction free bar magnet (hanging from a thread) which is not affected by
air currents (the bottle). Students may be concerned with the difficulty of
noticing small changes. This is a calibration issue that is part of the first
activity done with the magnetometer.
At conclusion of discussion/design pahse, hand out student pages for this
activity including design directions for a magnetometer.
(Magnetometer design adapted from:
Hand out following materials to each group:
- 1 clean plastic jar with lid (peanut butter jars work well)
- 1" long piece of a drinking straw.
- 1 piece index card (1" by 0.5 ").
- 1 bar magnet approximately 1" in length
- White glue
- Piece of metal
- Ring magnet
- Bar magnet
Lesson Development/Writing: Ed Eckel
Web Design: Theresa Valentine
Last Updated: 8/15/2000