1. Physics for Scientists and Engineers II, Summer Semester 2009 1 Lecture 15: June 24 th 2009 Physics for Scientists and Engineers II

2. Physics for Scientists and Engineers II, Summer Semester 2009 2 Motional emf (Rotational Motion O

3. Physics for Scientists and Engineers II, Summer Semester 2009 3 Lenz’s Law Assume for a moment that it was otherwise: then, a small increase in the magnetic field\ would create a current that produces a magnetic field that is increasing in the same direction. This increase would fuel another increase in current etc.  We would have a runaway effect in which the current would get so large that the ring would melt down. This cannot be so as can easily be seen From a conservation of energy view point. WRONG!!

4. Physics for Scientists and Engineers II, Summer Semester 2009 4 Lenz’s Law Correct !! The current induced creates a magnetic field that is opposite to  B.

5. Physics for Scientists and Engineers II, Summer Semester 2009 5 Faraday’s Law in General Form E is a non-conservative field (unlike the electrostatic field produced by stationary charges.

6. Physics for Scientists and Engineers II, Summer Semester 2009 6 Eddy Currents Eddy current demonstrations. Review