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For more information, please see full course syllabus of AP Physics C/Electricity and Magnetism
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Lecture Comments (1)

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Post by Windesson Almeida on November 15, 2011

you forgot to multiply by pi for increasing in B example.

Faraday's Law

  • Faraday’s law: When the magnetic flux through a loop changes with time, an electric current is induced in the loop. Faraday’s law states that the induced electromotive force (voltage) across the loop is minus the rate of change of flux.
  • Lenz’s law: This law gives the direction of the induced current in the loop due to a changing magnetic flux. It states that the current direction is such as to oppose the change in flux. For example, if the flux is decreasing with time, the current direction will be so as to produce a magnetic field in the same direction as the external magnetic field.
  • Faraday’s law provides the principle of operation of electrical generators; by rotating a coil in a uniform magnetic field (the coil being placed between the poles of a large magnet), a voltage (AC voltage) is induced across the coil.

Faraday's Law

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Faraday's Law 0:14
    • Coil Connected to Ammeter
    • Introducing a Magnet
    • Moving the Magnet Forward and Backward
    • Flux Increasing in Time
    • Induced Electro Motive Force EMF
    • Iron Core Square with Battery and Switch, Ammeter
    • Close the Switch, Current Appears
  • Lenz's Law 9:17
    • Wire with Current I and Wire Loop
    • Magnetic Field is Into the Page
    • Current Induced in Wire to Oppose Change in Flux
    • Example: Two Wires with Resistance and Uniform Magnetic Field
  • Increasing B 29:02
    • Coil of 100 Turns
    • B Perpendicular to Coil
    • Flux Through Each Turn
  • Rotating Coil 37:36
    • Consider a Big Magnet and Rectangular Coil with many Turns
    • Rotating Coil With Angular Velocity 'w'
  • Example 1: Loop
  • Example 2: Solenoid
  • Example 3: Wrapped Square