Clamp copper or aluminum disk to
pendulum
bob and swing between poles of magnet to show magnetic damping.
Similar
disk with slits cut to restrict circulation of eddy currents swings
freely.
NOTES
One of the disks is labeled "German
silver"
and, though solid, swings freely through the magnet. According to
Wikipedia,
German silver, also
known
as nickel silver, is an alloy of copper, nickel and sometimes
zinc (and no
silver).
The CRC says nickel silver has an electrical resistivity of 29 x 10-8
ohm-m -- as compared to 2.5 x 10-8 for aluminum and 1.6 x 10-8
for copper.
