Image: FaradaysLawWithPlates

Description: A counterexample to Faraday's Law when over-broadly interpreted. A wire (solid red lines) connects to two touching metal plates (silver) to form a circuit. The whole system sits in a uniform magnetic field, normal to the page. If the word "circuit" is interpreted as "primary path of current flow" (marked in red), then the magnetic flux through the "circuit" changes dramatically as the plates are rotated, yet the EMF is almost zero, which contradicts Faraday's Law. Faraday's Law only holds when the change in the circuit geometry directly corresponds to the motion of the material making it up. This condition is always true for thin wires but not always true for thick conducting plates. The correct EMF can be calculated using the Lorentz Force Equation directly. (This image and discussion are based on Feynman Lectures on Physics Vol. II page 17-3.)
Title: FaradaysLawWithPlates
Credit: Own work
Author: Sbyrnes321
Usage Terms: Creative Commons Zero, Public Domain Dedication
License: CC0
License Link: http://creativecommons.org/publicdomain/zero/1.0/deed.en
Attribution Required?: No