electromagnetic induction (emi)
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Electromagnetic Induction (EMI). AP Physics. Electromagnetic Induction (EMI). A changing magnetic field can induce a current in a circuit called the induced current . The corresponding emf that must be present to cause the current is the induced emf . What Causes Induction. - PowerPoint PPT PresentationTRANSCRIPT
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Electromagnetic Induction(EMI)
AP Physics
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Electromagnetic Induction (EMI)A changing magnetic field can induce a current in a circuit
called the induced current.
The corresponding emf that must be present to cause the current is the induced emf.
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What Causes Induction
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Magnetic Flux (φm)The amount of magnetic field there is in an area. (The number
of magnetic field lines in an area.)
Units of φm:
Only the components of
magnetic field that are perpendicular
to the area contribute to the
flux.
θ
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Magnetic Flux (φm)
θθ
θ
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Faraday’s LawBut wait…to have induction there must be a change in the magnetic field
(therefore a change in the magnetic flux)!!
“The induced emf in a circuit equals the rate of change of the magnetic flux through the circuit.”
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Flux ProblemThe U-shaped conductor lies perpendicular to a uniform magnetic field B
with magnitude B = 0.60 T, directed into the page. We lay a metal rod with length L = 0.10 m across the two arms of the conductor, forming a conducting loop, and move the rod to the right with constant speed v = 2.5 m/s. What is the magnitude of the resulting emf?
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GeneratorsA device that converts mechanical energy to electrical energy.
Alternating current generator (alternator)
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Lenz’s Law“The direction of any magnetically induced current or emf is such as to
oppose the direction of the phenomena causing it.”
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Lenz’s LawLenz’s Law requires some thinking!
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Motional emfThe induced emf in a circuit equals the rate of change of the
magnetic flux through the circuit.
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TransformersA device that converts voltage.
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Power Transmission
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Physics Rock BandElectromagnetic Induction is used to ROCK
OUT!!• Microphones
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Physics Rock BandElectromagnetic Induction is used to
ROCK OUT!!• Electric Guitar
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Physics Rock BandElectromagnetic
Induction is used to ROCK OUT!!
• Cassette Tapes (kickin’ it old school)