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How to Connect a Tangent Galvanometer

Connecting a tangent galvanometer is helpful when you need to measure the strength of an unknown electric current. Magnetic field experiments involving tangent galvanometers are common in college physics classes. A tangent galvanometer consists of a coil of insulated copper wire, a compass box and binding posts to connect a current source. The instrument works by comparing the perpendicular magnetic fields from the Earth and a current source.

Instructions

- 1
  Place your tangent galvanometer on a flat surface with no nearby magnetic sources.
- 2
  Rotate the tangent galvanometer until the plane of the coil is parallel to the north-south line of the compass.
- 3
  Connect the wire from your current source to the tangent galvanometer's binding posts. The first post corresponds to five turns of the coil wire, the second post corresponds to 10 turns and the third wire corresponds to 15 turns of the wire. The current produces a second magnetic field, which is perpendicular to the Earth's magnetic field.
- 4
  Read the angle on the compass' scale.
- 5
  Look up the current matching the angle in your tangent galvanometer's table.

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