Ammeter II

Make and ammeter out of a compass


It is possible to make an ammeter out of a compass by wrapping wire around the compass.



Wrap a coil of 100 turns of wire around the compass.

Wind the coil so that it passes over the north and south end of the compass, and yet still allows you to see the compass needle.

Use sandpaper to clean the insulation off the ends of the wire, they should appear like shiny clean copper.

Cut the aluminum foil into squares 5 cm on a side. Fold the aluminum foil into shapes 1 cm by 2.5 cm. Fold these shapes around the bare ends of the magnet wire.

To Do and Notice

Pass an unknown current through the coil of wire.

Notice that the compass needle deflects.
The larger the current the greater the deflection.

The needle deflects one way with positive current and the other way when the current reverses.

What's Going On.

When current flows in a coil it makes it into an electromagnet.

The magnetic compass needle will be deflected by this electromagnet.

The larger the current the stronger the magnetic field of the coil and the greater the deflection.

Scientific Explorations with Paul Doherty

© 2000

2 August 2000