The electromagnet consists of a
copper bar
wrapped around an iron core. A piece of copper-nickel alloy
across
the ends of the copper bar forms a thermocouple. One junction is
cooled by circulating water while the other is heated in the flame of
the
butane burner. The resulting Seebeck EMF produces a current in
the
copper bar sufficient to support the iron disk with up to 400 lbs.
hanging
from it.
NOTES
Demo can be set up so that a
person
can hang
from a wooden bar supported by the magnet.
Demagnetize iron core with large
magnet.
To determine the current in the
copper bar,
replace it with the 100-turn copper coil connected to a power
supply.
Vary the current until it supports the same weight the bar and
thermocouple
and multiply by 100.
