The Gauss’ Law
Electric field of
A point charge Q
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The Gauss’ Law
Electric field of
An infinitely long straight wire with charge density λ.
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The Gauss’ Law
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The Gauss’ Law
Electric field of
An infinitely large plane with charge density σ.
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The Gauss’ Law
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The Gauss’ Law
Electric field of
Solid insulator sphere with radius R, charge density ρ.
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The flux
The definition:
Flux Φ is defined at the “fluid”
velocity V times the cross section
A that the fluid flows through:
Φ = VA
Here both V and A are vectors.
The electric flux:
If one visualizes electric field lines as
some kind of fluid, one can define the
electric flux ΦE as field E times the cross
section A that the field flows through:
ΦE = EA = EA Cosθ
Here both E and A are vectors.
When E goes perpendicularly through A,
or in parallel with A’s direction,
ΦE = EA
Q? when the flux is 0?
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The Gauss’ Law
The Gauss’ Law:
The electric flux of an enclosed surface equals the amount of net
charge inside this surface divided by the permittivity constant εo.
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Point charge case
When the charge is a point charge:
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Point charge case
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Linear charge
When the charge is evenly distributed on a long straight line:
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Linear charge
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2-D charge
When the charge is evenly distributed on a large plane
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2-D charge
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Parallel-plate capacitor
Two large parallel plates form a capacitor: a device that stores charges.
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3-D charge
Charge on a conductive sphere.
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3-D charge
Charge on a conductive sphere.
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3-D charge
Charge in a non-conductive sphere.
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3-D charge
Charge in a non-conductive long rod.
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