Lenzs law Induced current produces a secondary magnetic field that is always opposed to the primary magnetic field that induced it an effect called Lenzs law Selfinductance L The alternating current in the coil generates an alternating magnetic field that induces an ID: 331008
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Slide1
Welcome
Slide2Slide3
Lenz's law
Induced current produces a secondary magnetic field that is always opposed to the primary magnetic field that induced it, an effect called
Lenz’s law
.Slide4
Self-inductance (L)
The alternating current in the coil generates an alternating magnetic field that induces an
emf
in the
same
circuit
.
The effect in which a changing current in a circuit induces an
emf
in the same circuit is referred to as
self-induction.Slide5Slide6Slide7
Eddy current
Eddy Currents are closed loops of induced current circulating in planes perpendicular to the magnetic flux. They normally travel parallel to the coil's winding and the flow is limited to the area of the inducing magnetic field.
Eddy Currents concentrate near to the surface adjacent to an excitation coil and their strength decreases with distance from the coil .
Eddy Current density decreases exponentially with depth. This phenomenon is known as the skin effect.Slide8
VideoSlide9Slide10
Metal connector
Cable
Why we don't use in electrical conduction? Slide11
Applications of
Eddy Currents
Magnetic Levitation (Maglev) Trains
Induced surface (“eddy”) currents produce field in opposite direction
Repels magnet
Levitates train
Maglev trains today can travel up to 310 mph
May eventually use superconducting loops to produce B-field
No power dissipation in resistance of wires!
N
S
rails
“eddy” currentSlide12
Metal Detectors
Can detect the presence
of metals
by using a transmitter coil to create an oscillating primary magnetic field.
This creates a secondary magnetic field due to eddy currents in the metal.
Can detect this secondary magnetic field by using a receiver coil.Slide13
Summary