Simple System to Measure the Earth's Magnetic Field

Abstract

Our aim in this proposal is to use Faraday's law of induction as a simple lecture demonstration to measure the Earths magnetic field (B). This will also enable the students to learn about how electric power is generated from rotational motion. Obviously the idea is not original, yet it may be attractive in the sense that no sophisticated devices are used. All the equipment needed is available in an elementary physics laboratory and is displayed in Fig. 1. The square wooden coil and handmade belt system to rotate the coil may require some craftsmanship; once made, it can be used for years. Using a compass, we first orient the table parallel to the direction of the Earth's horizontal component of B field. This is necessary to maximize the Earth's field which can suppress the noise effects as much as possible. It is preferable to minimize also any environmental effects by conducting the experiment away from power lines, if possible of course.