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ERIC Number: EJ1046777
Record Type: Journal
Publication Date: 2014-Dec
Pages: 1
Abstractor: As Provided
Reference Count: 11
ISBN: N/A
ISSN: ISSN-0031-921X
Magnetic Fields at the Center of Coils
Binder, Philippe; Hui, Kaleonui; Goldman, Jesse
Physics Teacher, v52 n9 p560 Dec 2014
In this note we synthesize and extend expressions for the magnetic field at the center of very short and very long current-carrying coils. Elementary physics textbooks present the following equation for the magnetic field inside a very long current-carrying coil (solenoid): B[subscript sol] = µ[subscript 0] (N/L) I, (1) where I is the current, N the number of windings, and L the coil length. It is obtained directly from Ampère's law, ignores end effects (hence it assumes an infinite coil), and is valid over the entire cross-section of the coil. The field is in the axial direction and it follows the right-hand rule convention. For N superposed loops of radius R each carrying current I, the multi-loop magnetic field at the center is given by B[subscript ml] = µ[subscript 0] (N/2R) I. (2)
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail: pubs@aapt.org; Web site: http://scitation.aip.org/tpt
Publication Type: Journal Articles; Reports - Research
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A