In my description, "string" should read "thread" or "monofilament". The finer the thread, also the longer the thread, the more sensitive the magnetometer. A long human hair is ideal. Just yank one from Guy's beard next time you see him, if he hasn't trimmed it lately. It is suspended inside the bottle to isolate it from air currents in the room. Lower floors are preferred to upper floors, to isolate it from strutural movement of the building. During an aurora, the mirror will twist back and forth slightly. It can be slow or fast, depending on the particular movement of the earth's magnetic field lines. Increasing the separation distance between the mirror/magnet and the projection screen will also improve the sensitivity. --- Chuck Hards <chuckhards@yahoo.com> wrote:
This is where a home-made magnetometer comes in handy.
You glue a tiny first-surface mirror to a magnet, suspend it on a string
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