Archivo: Eddy currents - explanation of drag force

Descripción: Diagram showing the forces on an electron in a metal sheet moving to the right under a magnet N {\displaystyle \mathbf {N} } , explaining eddy currents, and where the drag force on the sheet comes from. The red dot e 1 {\displaystyle \mathbf {e} _{\text{1}}} shows an electron in the metal under the magnet right after it has undergone a collision, and e 2 {\displaystyle \mathbf {e} _{\text{2}}} shows the same electron after it has been accelerated by the magnetic field. On average at e 1 {\displaystyle \mathbf {e} _{\text{1}}} the electron has the same velocity as the sheet v {\displaystyle \mathbf {v} } (black arrow). in the + x {\displaystyle +\mathbf {x} } direction. The magnetic field ( B {\displaystyle \mathbf {B} } , green arrow) of the magnet's North pole N is directed down in the − y {\displaystyle -\mathbf {y} } direction. The magnetic field exerts a Lorentz force on the electron (pink arrow) of F 1 = − e ( v × B ) {\displaystyle \mathbf {F} _{\text{1}}=-e(\mathbf {v} \times \mathbf {B} )} , where e is the electron's charge. Since the electron has a negative charge, from the right hand rule this is directed in the + y {\displaystyle +\mathbf {y} } direction. At e 2 {\displaystyle \mathbf {e} _{\text{2}}} this force gives the electron a component of velocity in the sideways direction ( v 2 {\displaystyle \mathbf {v} _{\text{2}}} . black arrow) The magnetic field acting on this sideways velocity, then exerts a Lorentz force on the particle of F 2 = − e ( v 2 × B ) {\displaystyle \mathbf {F} _{\text{2}}=-e(\mathbf {v} _{\text{2}}\times \mathbf {B} )} . From the right hand rule, this is directed in the − x {\displaystyle -\mathbf {x} } , opposite to the velocity v {\displaystyle \mathbf {v} } of the metal sheet. This force accelerates the electron giving it a component of velocity opposite to the sheet. Collisions of these electrons with the atoms of the sheet exert a drag force on the sheet.
Título: Eddy currents - explanation of drag force
Créditos: Trabajo propio
Autor(a): Chetvorno
Términos de Uso: Creative Commons Zero, Public Domain Dedication
Licencia: CC0
Enlace de Licencia: http://creativecommons.org/publicdomain/zero/1.0/deed.en
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