18_1?Electromagnetic?Induction:?Magnetic?Flux? and?Lenz?s?Law Apr/4/2016 M.?Burkardt?? NMSU?? PHYS?214?? Spring?2016 1 Phys214 Electricity & Magnetism Electromagnetic Induction: Magnetic Flux, Lenz?s Law Motivation Hans-Christian ?rsted (1820): electric current causes a magnetic field Michael Faraday Can a magnetic field produce an electric field (and thus a current in a conductor)? Changing magnetic fields are sources of an emf and electric currents. Lecture Outline Currents (moving electric charges) Magnetic Fields Current-carrying wires are sources of magnetic fields. Card Readers Physics in Everyday Life A credit card stores it information as a magnetic pattern on the back of the card. Why is it necessary to ?swipe? the card, instead of holding