This article is a modified version which was published originally in German in the journal: Physik in unserer Zeit 35 (2004), 272-273
Figure 1 The motor
A fast, high-tech, low cost electric motor construction
H Joachim Schlichting and Christian Ucke (English translation by Jonathan Williams)
Electrical experiments are the clearest and most exciting of those offered by physics.
If a combination of a cylindrical magnet and a screw is suspended from the
terminal of a battery and a conducting connection is made with the other
terminal, then this assembly begins to rotate. It is not only the simplest but also
the fastest electrical motor to construct.
Electrical motors are mostly seen as complicated systems of
coiled wire and magnets. Since one expects something
complex from something complicated, one is not more
surprised by the possibility to make something moving from
an inanimate object.
One sees surprise and fascination, not only amongst experts
when, before one's eyes, a motor is assembled in a few
seconds from a battery, a steel screw or nail, a cylindrical
magnet and a short wire and set in rotation. The magnet,
through its attractive power, attaches to the screw to make a
rotor, and the screw, which has itself become magnetised, is
suspended from the battery pole. Two constructive exercises
are illustrated: on the one hand the magnet holds essential
parts of the motor together and on the other hand it provides a
low friction connection between the rotor and the battery. The
bearing on the other side of the rotor is compensated by
gravity which ensures that the rotor stays vertical and, due to
the air bearing formed, generates the lowest possible friction.
In the example in Figure 1 is used a very strong neodymium magnet (NeFeB) whose surface is
chrome-plated and therefore conducts the current.
The hands provide the rest of the construction: One hand presses the end of the current carrying
wire to the second battery pole whilst the thumb and finger of