## Lecture 8: Faraday's Law of Induction

February 13, 2018

• Read: 27.1--27.3, 27.6, 29.1--29.4 (up to the middle of p. 548)
• Study: Eqs. 27.1, 27.2; Exs 27.3, 27.5, 27.10
• Skim: Sections 29.1 and 29.2
• Ignore: Diamagnetism'' in Section 27.6 (p. 519).

### Objectives

• (Continuing objective) Describe applications of the concepts of induction, waves, and light to everyday real life'' situations.
• For a given simple magnetic field and a surface, calculate the magnetic flux.
• Given a situation in which there is a changing magnetic flux, apply Faraday's law to relate the emf, current, or circulation of the $\vec{E}$-field to the properties of the magnetic field and of the coil.
• Distinguish situations for which there is or is not an induced emf.
• Apply Lenz's Law to determine the direction of induced emf, electrical currents, eddy currents, magnetic fields, or forces.

### Homework

• Wednesday's Assigned Problems: A23, A24, A25; CH 27: 1, 2, 15, 17, 33, 35, 45

Note: The answers in the back of the book for CH 27, problems 33 and 35 have negagive signs that are completely meaningless. Please ignore the minus signs for the answers to those two problems.

• Monday's Hand-In Problems: A28, X2 (online); CH 14: 18, 46; CH 27: 18, 34, 38, 44; CH 29: 22

Note: Electronic link to problem X2 can be found on the calendar page for Lecture 9.

### Videos of example problems

To see the problem statement, click on the link below. To play the video example, click on the underlined words "Video Demonstration" near the top of the page with the problem statement.
• Example #1: Determining the emf in a loop near a long wire with a current that drops to 0 in a specified time interval. Lenz's Law in here as well as Faraday. Note: This problem involves a non-uniform B-field, which is similar to one of your hand-in problems.
• Example #2: Determining the emf in a loop moving into a region with magnetic field.