Day 2: Design and Build a Magnetometer
Lesson Plan

Objective:

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.)

Discussion:

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: http://image.gsfc.nasa.gov/poetry/workbook/page9.html)

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
• Thread
• Scissors
• Piece of metal
• Balloon
• Ring magnet
• Bar magnet

---

Lesson Development/Writing: Ed Eckel
Web Design: Theresa Valentine
Last Updated: 8/15/2000