Electric Field Lines Equipotential Lines

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Electric Field LinesEquipotential Lines
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Direction of lines ? direction of
force on positive test charge
Concentration of lines ?
relative strength of field
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Electric field for 2 positive charges
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Electric Fields
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Uniform Electric Field (E)
Constant field force acceleration
F Eq
a F/m
Eq/m
(V diff. of potential)
E V/d
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Electron and proton in a uniform electric field
Compare e and p as to direction of motion,
force, acceleration, velocity, displacement
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Electric field inside a good conductor is zero
in the static situation.
Any net charge is on the surfaces.
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Charge on inner surface the same as charge on the
object inside the conductor (net 0)
If charge on outside conductor is 2 µC and
charge on inside object is 1 µC
-1 µC
inner surface outer surface
3 µC
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Electric field outside conductor
same as if point charge, kQ/r2
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Two charged. isolated spheres are far apart. The
larger sphere has twice the radius of the smaller
sphere.
If magnitudes of electric fields just outside the
surfaces are the same, how do the charges compare?
charge is 4 times larger for large sphere
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Electric Field inside a Conductor
Field inside is zero
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Electric field inside a hollow metal box 0
Used to shield from external fields
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application electric shielding
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Sharing of Charge
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Charge distributes proportional to surface areas.
At equilibrium, each object at same potential.
(diff potential 0)
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Large sphere has twice the diameter of small
sphere. Original charge on large sphere is q.
Small sphere is neutral.
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Charge on each after connected?
4/5 q 1/5 q
How does potential of each compare?
at same potential
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Equipotential Line (Surface)
Line (Surface) on which all the points are at
the same potential
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Equipotential lines perpendicular to field lines
Work to move along equipotential line 0
Surface of a conductor is equipotential.
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E
F
a qE/m
t (2mv sin ?)/qE
d (2mv2 sin ? cos ?)/qE