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Eddy currents are produced in a conductor when it is subjected to ___________.
a changing magnetic field
a uniform magnetic field
a constant magnetic field
an electrostatic field
a changing magnetic field
Eddy currents are loops of electrical current induced within a conductor when the magnetic flux linked with it changes. According to Faraday's law of electromagnetic induction, a time-varying magnetic field induces an electromotive force (EMF), which drives these currents in the conductor.
Eddy currents are loops of electrical current induced within a conductor when the magnetic flux linked with it changes. According to Faraday's law of electromagnetic induction, a time-varying magnetic field induces an electromotive force (EMF), which drives these currents in the conductor.
Think of eddy currents like ripples in a pond created when you move your hand through water; the water (conductor) swirls in response to the disturbance (changing magnetic field).
EDDY: E-lectromagnetic D-isturbance D-rives Y-ield (currents)
e=тИТdtd╬жтАЛ тАФ Faraday's Law of Induction, showing EMF depends on the rate of change of magnetic flux.
P=I2R тАФ Power dissipation formula showing that eddy currents generate heat proportional to the square of the current.
When a conductor is placed in a changing magnetic field, the magnetic flux through its cross-section changes over time. This change induces an EMF e=тИТdtd╬жтАЛ inside the material. Because the conductor has finite resistance, these EMFs drive circulating currents called eddy currents, which generate heat and create their own magnetic field that opposes the change in flux (Lenz's Law).
Eddy currents always oppose the cause that produced them, following Lenz's Law.
They are also known as Foucault currents.
Higher conductivity in a material leads to stronger eddy currents.
Laminated cores are used in electrical machines to minimize eddy current losses.
Used for magnetic braking in heavy trains.
Enables induction heating for cooking.
Used in speedometers and galvanometers for damping oscillations.
Causes unwanted heat in transformer cores.
Reduces the efficiency of electrical machines.
Increases energy loss due to ohmic heating (I2R loss).
Induction furnaces for melting metals.
Electromagnetic damping in meters.
Metal detectors used in security.
Induction cooktops.
Option B and C are incorrect because a uniform or constant magnetic field does not induce an EMF, as dtd╬жтАЛ=0.
Option D is incorrect because electrostatic fields deal with stationary charges, not magnetic induction.
A is correct тАФ Eddy currents are induced exclusively by a changing magnetic field which causes a rate of change of magnetic flux.
Always remember that stationary magnetic fields produce static forces, but induction requires motion or change: if the flux is constant, the induction is zero.