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ERIC Number: EJ1082761
Record Type: Journal
Publication Date: 2015-Dec
Pages: 4
Abstractor: As Provided
ISSN: ISSN-0031-921X
The Expected but Well-Hidden EMF in the Jumping Wire Experiment and Its Unexpected Role
Donoso, G.; Ladera, C. L.
Physics Teacher, v53 n9 p550-553 Dec 2015
As presented in physics textbooks, as well as in a few papers, the typical example of an induced motional electromotive force e[subscript mot] = "Blv" consists of a conductive rod of length "l" frictionlessly sliding with speed v along parallel wires within an orthogonal and constant uniform magnetic field of magnitude "B." End-of-chapter problems, variants of that sliding rod, are additionally posed in those textbooks. The horizontal "jumping wire" of length "l" carrying a current "i" that is tossed upward by a magnetic force, in a transverse horizontal magnetic field "B," is an important variant, as evidenced by its popularity as a demonstration experiment (with numerous videos and blogs posted on the web). A simplistic account of the wire-jump experiment is often given exclusively in terms of the well-known magnetic force F = "i"l × B that propels the wire upward. The jumping wire is an eye-catching demonstration for both students and the public, and it indeed deserves to be analyzed in greater detail, since as shown below it hides fundamental and interesting physics, certainly much more than what the eye catches.
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A