1. Physics 121: Electricity & Magnetism – Lecture 11 Carsten Denker NJIT Physics Department Center for Solar–Terrestrial Research

2. April 4, 2007Center for Solar-Terrestrial Research Faraday’s Law Induced current Induced EMF Magnetic flux Faraday’s law The magnitude of the EMF induced in a conducting loop is equal to the rate at which the magnetic flux  B through that loop changes with time.

3. April 4, 2007Center for Solar-Terrestrial Research Lenz’s Law An induced current has a direction such that the magnetic field due to the current opposes the change in the magnetic flux that induces the current.

4. April 4, 2007Center for Solar-Terrestrial Research Induction and Energy Transfer

5. April 4, 2007Center for Solar-Terrestrial Research Induced Electric Fields Faraday’s law A changing magnetic field produces an electric field!

6. April 4, 2007Center for Solar-Terrestrial Research Inductors and Inductance Inductance Solenoid Self-induced EMF An induced EMF appears in any coil in which the current is changing.

7. April 4, 2007Center for Solar-Terrestrial Research RL Circuits RL circuit Rise of current Inductive time constant Decay of current Initially, an inductor acts to oppose changes in the current through it. A long time later, it acts like ordinary connecting wire.

8. April 4, 2007Center for Solar-Terrestrial Research Energy Stored in a Magnetic Field Magnetic energy