A recent item in Physics Challenges for Teachers and Students1 presented a problem of a metal rod (mass M) sliding on frictionless, parallel conducting rails (of negligible resistance and separated by a distance L) in the presence of a downwardly directed uniform external magnetic field B. A resistor R bridges the rails, thereby completing the circuit. This problem can also be found in Griffiths' text Introduction to Electrodynamics, 3rd ed. (Problem 7.7).2

Topics
Electrodynamics, Teaching
1.
Boris
Korsunsky
, “
Physics Challenges for Teachers and Students: Track and field
,”
Phys. Teach.
41
,
124
(Feb.
2003
).
Google Scholar
 
2.
David J. Griffiths, Introduction to Electrodynamics, 3rd ed. (Prentice Hall, Upper Saddle River, NJ, 1999), p. 299.
3.
Chandralekha
Singh
, “
When physical intuition fails
,”
Am. J. Phys.
70
,
1103
–
1109
(
2002
).
Google Scholar
Crossref
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© 2004 American Association of Physics Teachers.
2004
American Association of Physics Teachers
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