A.S – due Friday, 12/19/14

  What happens to electrons as they move through a magnetic field?  What would happen if there were a LOT of electrons…like in a wire… Things to think about…

 What happens…

 Induced (motional) emf

  Known : An electric current produces a magnetic field  Known : A wire moving through (perpendicular to) a magnetic field will develop a potential difference across its ends (Induced emf)  More difficult? Producing a current… Electromagnetic Induction

  What happens to the current when:  North end moved into the loop?  North end moved out of the loop?  South end moved into the loop?  South end moved out of the loop?  North end held above the plane of the loop?  Magnet held inside the loop?  Magnet moved in/out of the loop at a different speed than before? Observations

  As these increase, so will the current:  The relative speed of the magnet with respect to the loop/coil  Strength of the magnetic field  Number of turns in the coil  Area of the loop  ALSO:  Angle of the magnetic field relative to the plane of the loop.  At an angle 90° (field perpendicular to the plane of the loop), the current will be the maximum possible for the conditions Variables that affect current:

  British Physicist and Chemist—born 1791, died 1867  Self-taught…discovered many concepts, had difficulties with some of the math  Discovered Electromagnetic Induction in 1831  (also devised the laws relating to electrolysis and the deposition of ions onto metals through the use of electricity)  Found the connecting link between each of the observations we just made…  The relevant law that bears his name (Faraday’s Law) relates to electromagnetism Michael Faraday

 Magnetic Flux

  Units of flux = Weber (Wb)  Conceptual visualization: flux is the number of magnetic field lines that are passing through the plane of the loop  Increase the flux by:  Increasing the area of the loop  Increasing the strength of the field (more field lines…)  Making the loop and field lines more perpendicular Magnetic Flux

 Magnetic Flux Linkage

  A loop of area 2.00 cm 2 is in a constant magnetic field of T. What is the magnetic flux through the loop in each of the following situations:  When the loop is perpendicular to the field  When the loop is parallel to the field  When the normal to the loop and the field have an angle of 60.0° between them? Sample Problem

 Faraday’s Law

  The magnetic field through a single loop of area m 2 is changing at a rate of 4.25 T·s -1. What is the induced emf in the loop? Sample Problem

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