Physics

"The Electric Field Mill & Earth’s Electric Potential"

During the 17th century Benjamin Franklin proposed flying a kite in a thunderstorm to show that lightning has electrical properties. Today we know that lightning is the form in which electrostatic discharge occurs on Earth and the idea that the Earth has atmospheric electricity. Atmospheric electricity is a difficult thing to study and even today there is no concrete explanation on how thunderclouds charge.

Electrostatic fields are present throughout the atmosphere. Measuring the strength of these electric fields near the Earth’s surface is becoming more common due to technological advancements.

We would like to measure the Earth’s electric potential. This will be done by studying electric fields and building an electric field mill. The electric field mill is a device based on electrostatic induction and capable of measuring the strength of an electric field.

The electric field mill (also known as a generating voltmeter) is used to measure the strength of an electric field around a Van de Graaff generator and within particle accelerators, to name a few. The advantage of using this device is the fact that no wires are required to measure the electric field between two objects. One can therefore determine the electric potential between the Earth’s surface and its atmosphere.

Participants

• Mr. Louwrens van Schalkwyk
• Mr. Johan Janse van Rensburg
• Dr. Walter Meyer
• Dr. Francois Engelbrecht