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The Strange World of Dr. Lentz. W14D1. Faraday and Lentz. Good friends??. Calendar Thing. Remember Flux?. Ring around the Ring. From Faraday. This - d B / dt is important. NC. So, continuing. Last Time - Maxwell. Coulomb/Gauss Gauss – Magnetism Faraday’s Law
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Faraday and Lentz Good friends??
Ring around the Ring
From Faraday This -dB/dt is important NC
Last Time - Maxwell Coulomb/Gauss Gauss – Magnetism Faraday’s Law Extended Ampere’s Law
A Parallel Universe Lentz’s Law
Induced Magnetic Fields always FIGHT to stop what you are trying to do! i.e... Murphy’s Law for Magnets Lenz’s Law
Example of Nasty Lenz The induced magnetic field opposes the field that does the inducing!
From Before .. as a reminder This -dB/dt is important
The power supply is slowly turned up, increasing the current in the solenoid. The initial B is show on the diagram. The current increases so B increases as well by dB in time dt. Effect is a field reduction caused by the induced current which must be opposing the original current (- sign). The net emf is reduced as is the current. (Ohm’s Law). The induced current opposes I. B The total emf is changed (reduced ) by this amount.
The power supply is slowly turned up, increasing the current in the solenoid. B What does Lentz tell us??? The total emf is changed (reduced ) by this amount.
Remember the Pipe Demo S N Aluminum Pipe • Do you remember it? • Can you explain it? • Mini Activity on the Pipe • Whiteboard Presentation
Let’s look at how a “transformer” might work. ACTIVITY #2