Magnetic Induction

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Magnetic Induction
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Key Points about Induction

• If the current in the primary circuit is
  constant, then the current in the secondary
  circuit is zero.
• When the magnetic field in the secondary circuit
  increases the current flows in one direction, and
  when the magnetic field decreases the current
  flows in the opposite direction.
• The magnitude of the induced current and emf are
  proportional to the rate of change of the
  magnetic field.

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Induced Current Produced by a Moving Magnet
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The Magnetic Flux Through a Loop
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Magnetic Flux
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Find the flux through each side of the box.
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Which flux(es) change(s) with time?
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When will the emf and the magnetic flux be the
greatest?
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A Dynamic Microphone
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The Pickup on an Electric Guitar
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Magnetic Tape Recording
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Induction Loop for the Hearing Impaired
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Applying Lenzs Law to a Magnet Moving Toward and
Away From a Current Loop
The polarity of the induced emf in a loop is such
that it produces a current whose magnetic field
opposes the change in magnetic flux through the
loop. That is, the induced current is in a
direction such that the induced magnetic field
attempts to maintain the original flux through
the loop.
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How do the accelerations compare?
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Lenzs Law Applied to a Decreasing Magnetic Field
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Motional emf
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Which plate is positively charge if the field
increases?
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What are the induced currents if I increases?
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Eddy Currents
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Quantitative Information from Lenz and Faraday
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Find B, F, W, E, i, and v.
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What are the induced current and the speed of the
rod?
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An Electric Generator
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A Simple Electric Motor
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Induced emf of a Rotating Coil