PHYS.1440 Lecture 22 A.Danylov Department of Physics and Applied Physics Lecture 22 Chapter 30 Induced Electric Field Physics II This fool said some nonsense that the electric field can be produced from the magnetic field. Course website: https://sites.uml.edu/andriy-danylov/teaching/physics-ii/
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• Presence of a permanent magnet makes the guitar wire a magnet.
• When the magnetic guitar wire vibrates, it changes the magnetic flux in the coil.
• This flux induces a current in the coil which exactly follow the vibrations of the guitar wire.
• This current is fed to the amplifier and we can hear the sound of vibration of the guitar wire.
How Microphone works?
• When a sound wave strikes the diaphragm, a coil fixed to the diaphragm vibrates over a stationary bar magnet, changing the flux in the coil and induced an emf in the coil which is then amplified and sent to speakers.
The current through the solenoidcreates an upward pointing magneticfield.As the current is increasing, B isincreasing, so it must induce an electricfield.
So, the induced current is clockwise.The induced electric field musttherefore be clockwise around themagnetic field lines.
EB
Eternal dance
HowcanwefindadirectionoftheinducedE?
‐ Imagine a conducting loop in thesolenoid and use Lenz’s rule to find Iinddirection and that is Eind direction.