Day 6 More Meters
Build your own meter.
Wrap a coil of wire around a circular form to make an electromagnet, then suspend a magnet inside this coil. The suspended magnet will rotate showing the direction and magnitude of the electric current.
Build a meter using a compass.
You can also build a meter starting with a magnetic compass. This has advantages because the compass comes with a scale calibrated in angle.
Wind the coil over the north and south direction of the compass and then rotate the compass so that it points north south when there is no current in the wire.
When a current flows through the wire the needle of the compass will be deflected. When the compass is deflected by 45 degrees the magnetic field from the coil is equal to the earth's magnetic field.