Manual
11
Physical Experiments on the Air-Cushion Table
1.2. Principle Uses of the Air-Cushion Table
The system kit allows for
- nearly frictionless movement of the hover
discs
- through the air cushion
- modeling the interactions between the micro-
objects and the field
- through magnetic forces
- through electrical forces
- by tilting the experiment surface
- excellent visibility of all experiments
- due to projection with the overhead
projector
- little preparation work
- due to clear and simple system setup
- since only few adjustments required
The experimenter can continually adjust the in-
fluence factors and directly intervene in the ex-
perimental procedure.
All of this ensures a large variety of uses, prefer-
ably to demonstrate the behavior of individual
microobjects or microobject systems. Therefore
it becomes possible to create moving, vivid and
highly simplified models of complicated physi-
cal objects and phenomena, which one cannot ob-
serve directly.
Some of the forces taking effect in model exper-
iments vary considerably from those occurring
between the real objects. In many cases, howev-
er, the force-distance relations are very similar,
so that special attention only needs to be paid to
them in quantitative experiments.
Despite this limitation, the air-cushion table is a
versatile, effective and appealing teaching aid
when handled by a qualified and methodologi-
cally skilled experimenter. When teachers have
fully understood the operation of the system and
follow the operating instructions for the system
described below, they can demonstrate experi-
ments with physically convincing and effective
results.
1.3. Setup of the Air-Cushion Table
The
air-cushion table is made up of a frame and
a pressure chamber. The cover plate of the pres-
sure chamber has 1089 holes (∅ 0.8 mm). This
is the experiment surface. The side of the pres-
sure chamber where the impulse valve is located
is connected to the fan using the tube. The exper-
iment surface can be set to the horizontal or in-
clined position by means of two adjusting screws
and verified by means of the vertically arranged
spirit levels.
Five different types of hover discs are supplied
with the air-cushion table. They are made of col-
ored, transparent plastic or aluminum discs, onto
which cylindrical, ceramic magnets are attached.
Carried by the air cushion, these hover discs sim-
ulate the moving objects.
The experiment surface is delimited by a flat plas-
tic frame. It is also possible to attach magnetic
barriers allowing for almost fully elastic colli-
sions of the hover discs. Therefore it becomes
possible to demonstrate interactions with the ves-
sel walls.
To create an electric field, two rod-type electrodes
can be placed on the experiment surface. A mod-
el effect of an electric field can also be attained
by inclining the air-cushion table to the desired
degree.
The impulse valve can be used to create an air-
flow parallel to the experiment surface influenc-
ing the motion of the hover discs. This can be
used to increase the speed of the hover discs.
The fan ensures a sufficient air cushion over the
experiment surface. Its performance is continu-
ously adjustable and can be adapted to the condi-
tions of the experiment. The fan is equipped with
a delivery connection and a suction connection.
While experimenting with the air-cushion table,
the delivery connection is used, the suction con-
nection can be used for other physical experiments
(e.g. with the transparency panel apparatus).
The lattice model is made up of 25 ceramic mag-
nets, which are suspended by thin steel wires. This
system oscillates with little absorption. It is used
to demonstrate e.g. the interaction of a metal lat-
tice with the moving charge carriers as a model.
It is inserted into the holding device in the same
way as the Plexiglas plate. The height in which
these components are located above the experi-
ment surface can be adjusted as individually suit-
ed for each experiment by means of the setscrew.
The settings can be easily reproduced using the
scale marks.