Description

This apparatus is designed to enable students to
investigate the properties of an a.c. generator as
used in a bicycle dynamo.
A permanent magnet rotates between metal
plates linked to a coil of wire. As the field through
the coil changes a current is induced in the coil
and this is brought out to two 4mm sockets.
The unit is transparent to show all the inner
workings and is a convenient hand held device
with a direct drive (no gearing) to the rotating
magnet. The output can be displayed on a centrezero
moving coil voltmeter or oscilloscope.
The output swings from + to – each revolution and
is about 0.5V peak to peak with the magnitude
varying with speed. Because of the geometry of
the mechanism the output is not a simple sine
wave and if a PC oscilloscope is used to store the
trace, the waveform can be studied in more detail.
Because the magnets are attracted to the steel
core pieces, if the handle is eased just past the
mid-position they oscillate as a damped simple
harmonic motion with a PC oscilloscope trace that
can be analysed at senior levels.
Dimensions:
125 × 20 × 10mm pk of 5
20g each