A calculation is presented that quantitatively accounts for the terminal velocity of a cylindrical magnet falling through a long copper or aluminum pipe. The experiment and the theory are a dramatic illustration of Faraday’s and Lenz’s laws.
REFERENCES
1.
W. M.
Saslow
, “Maxwell’s theory of eddy currents in thin conducting sheets and applications to electromagnetic shielding and MAGLEV
,” Am. J. Phys.
60
, 693
–711
(1992
).2.
C. S.
MacLatchy
, P.
Backman
, and L.
Bogan
, “A quantitative magnetic braking experiment
,” Am. J. Phys.
61
, 1096
–1101
(1993
).3.
K. D.
Hahn
, E. M.
Johnson
, A.
Brokken
, and S.
Baldwin
, “Eddy current damping of a magnet moving through a pipe
,” Am. J. Phys.
66
, 1066
–1076
(1998
).4.
J. A.
Palesko
, M.
Cesky
, and S.
Huertas
, “Lenz’s law and dimensional analysis
,” Am. J. Phys.
73
, 37
–39
(2005
).5.
6.
N. I.
Kochkin
and M. G.
Chirkévitch
, Prontuário de Física Elementar
(MIR
, Moscow
, 1986
).7.
We used the Phywe digital teslameter, http://www.phywe.de/>.
© 2006 American Association of Physics Teachers.
2006
American Association of Physics Teachers
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.