1. Faraday’s Law: Generalized A loop moving in a field has a current induced (Think F=qvB) If the loop is stationary, and the magnet moves, a current is still created! Why? Charges in the loop “see” a changing magnetic field, and this creates an electric field. This electric field moves the charges and causes the current.

2. Alternate View of Faraday’s Law Changes in magnetic flux induce an e-field in the conductor. This e-field exerts a force on the free electrons, pushing the charges around. F=qE Recall –emf is the work per unit charge  =W/q=d  /dt –and that work = Fl where l is some arbitrary path length Therefore, around any closed path of length l

3. Exercise: A loop of wire surrounds an ideal solenoid Solenoid has 15,000 turns/meter and a radius of 2cm. The wire loop has a radius of 4cm. The current in the solenoid is increased at a rate of 10A/s What is the magnitude of the induced e-field at each position along the wire?

4. From Faraday’s Law (Absolute values b/c only care about magnitude) Since solenoid is ideal, B-field exists only inside it. Therefore, flux through the wire is

5. Therefore,