Academic journal article The Science Teacher

Galvanometer

Academic journal article The Science Teacher

Galvanometer

Article excerpt

...adapted from ELECTRICITY #19 by TOPS Learning Systems

1. Coil 3 meters of thin, insulated wire around the neck of a baby foodjar. Twist to secure tightly, then strip insulation from the leads.

2. Tape a small magnet on a toothpick or stiff wire, and suspend it in the mouth of the jar.

3. Notch the end of a straw, and tape it over the magnet. Weight the top with enough clay so it rocks back and forth about 1 swing/second.

4. Danish scientist Hans Christian Orsted (1777-1851) discovered a valuable property of electricity. Connect your galvanometer to a battery, and tell what he learned.

[ILLUSTRATION OMITTED]

OBJECTIVE

To construct a galvanometer. To understand that moving electrons create an associated magnetlcfield.

EXTENSION

What variables can you adjust to make a more sensitive galvanometer? Design and build an Instrument that detects current In an old battery that Is almost dead. (a) Coll more wire around the neck of the jar. Doubling or tripling the number of turns, doubles or triples the sensitivity, (b) Coll the wire closer to the magnet by using a smaller diameter jar mouth, (c) Add more clay to the top of the straw so It leans far to one side, but does not fall over. Then roll the support pivot ever so slightly across the thickness of the magnet In the direction of the lean, bringing the straw back to near vertical with extremely slow oscillations. …

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