The C objects look like spark-timer spark generators. The visible coil
forms an electromagnetic mechanical vibrator. In the box is a HV
transformer. This essentially works like the points/coil of a car. The
spark rate is not necessarily known, but if it is steady you can show how an
object either keeps constant velocity or constant acceleration, or whatever.
If this is what they are, and I haven't given enough info to make its use
clear, write back.
J is a resistance substitution box. On the outside the brass plugs provide
a low resistance connection point to point. On the inside each point is
connected to the next by a resistor whose value is the number printed on the
top. When you remove the brass plug, current has to go through the
resistor. The total resistance from one terminal to the other is the sum of
the values of the plugs removed. Often some of the internal resistors have
been burned up by students who put too much current through them. Also, the
brass plugs are often lost. If you have all the plugs and if none of the
resistors are burned up, you have a really nice resistor substitution box.
H can be used to spin things fairly fast. For example you can put a
red/green/blue segmented disk on the top axle, and spin it fast enough to
see white.
G objects look like the intent is to show the magnetic field around a wire
by setting compasses around the wire. Looks like the top left has the
compasses built in. Ones on left also allow a compass to be slid under the
horizontal portion of wire. These things require substantial current. I
don't have an alternative use.
For K, can you hook it to compressed air and use it as an air puck?
Probably won't be well balanced unless you remove valve and replace with a
lighter weight tube.
Michael Edmiston
Professor of Physics and Chemistry
Bluffton College, Bluffton, Ohio 45817