Day 2: Design and Build a Magnetometer
We are going to build a device for detecting the presence of a
magnetic field: a magnetometer. We will use a magnet as the 'sensor',
attach it to a small card, and hang it from a thread in a jar. We will
conclude by testing the magnetometer with various materials.
Materials for each student:
- 1 clear, wide mouth, plastic jar with screw on lid
- 3 feet of sewing thread
- 1 small bar magnet
- 1 piece index card
- 1 piece of soda straw
- Clean the jar thoroughly and remove labeling.
- Pierce a small hole in the center of the cap.
- Glue the magnet to the center of the top edge of the card.
- Label the ends of the magnet by marking the card. We suggest using designations like "A" and "B" such that all A's attract all B's.
- Glue the piece of soda straw to the top of the magnet.
- Thread the thread through the soda straw and tie it into a small triangle with 2 inch sides.
- Tie remaining thread to the top of the triangle in #7 and thread it through the hole in the cap.
- Put the jar top and bottom together so that the 'sensor card' is free to swing in response to the magnetic fields.
- Glue the thread through the cap in place.
Practice Using the Magnetometer:
Work with the magnetometer and materials provided to you. Answer the
following questions. Cite your test procedure, evidence, and the reasoning
that supports your answer.
- What is the magnet in the bottle sensing?
- How long must you wait after placing magnetometer to get a
reliable orientation observation?
- How does rotating the bottle while making an observation
affect the reliability of the measurement?
- How does your presence in the vicinity affect the reliability of the measurement?
- Can non-magnetic materials cause deflections?
- How far must one magnetometer be from another in order to keep them from interfering?
Lesson Development/Writing: Ed Eckel
Web Design: Theresa Valentine
Last Updated: 8/15/2000