Maxwell

1
Maxwells Equations (so far)
Not complete
Not complete
2
Can a distribution of static charges make this
field?
Electrostatic forces are conservative. The
change in potential around a loop must be zero.
3
BUT This is only true for Coulomb fields
(fields caused by stationary charges).
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There is another way to make electric fields.
5
Where there is a time-varying magnetic field,
there is also a curly electric field.
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Curly electric field (both inside and outside
solenoid)
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No curly electric field
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We call the curly electric fields Non-Coulomb
electric fields ENC
They are related to magnetic fields that are
changing in time
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Which direction does the electric field curl?
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Which direction does the electric field curl?
Right thumb along Fingers curl in direction of
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Which direction does the electric field curl?
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Which direction does the electric field curl?
13
Which direction does the electric field curl?
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Which direction does the electric field curl?
15
What if we put a conducting wire around the
solenoid?
A current is induced in the wire.
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Solenoid B increasing
Metal wire
How big is the current i2?
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EMF (ElectroMotive Force)
EMF is actually not a force. It is the energy
per unit charge added to a circuit during a
single round trip.
EMF
Units Volts
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Solenoid B increasing
Metal wire
EMF
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Solenoid B increasing
Metal wire
(Ohms Law)
??
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We can measure ENC by measuring the induced
current.
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Experiments i2 is only present when i1 is
changing.
EMF
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Experiments i2 is proportional to the area of
the solenoid.
EMF
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Faradays Law
EMF
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Faradays Law
EMF
The EMF around a closed path is equal to the rate
of change of the magnetic flux inside the path.
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Faradays Law
The EMF around a closed path is equal to the rate
of change of the magnetic flux inside the path.