Ph-204 Chap 21
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Ph-204 Chap 21
Chapter 21 Electric Potential Energy
Electric Potential Energy and Electric Potential,
created by charges and exists at every point surrounding those charges.
When a charge
is brought near these charges:
it acquires an electric potential energy
at a point where the other charges have created an electric potential V.
Energy is conserved for a charged particle in an electric potential:
ΔK = -qΔV
Potential differences ΔV are created by a separation of charge. Two important sources of potential difference are:
1.A battery, which uses chemical means to separate charge and produce a potential difference.
2.The opposite charges on the plates of a capacitor, which create a potential difference between the plates.
The electrical potential of a point charge
conductor in electrostatic equilibrium
1.Any excess charge is on the surface.
2.The electric field inside is zero.
3.The exterior electric field is perpendicular to the surface.
4.The field strength is largest at sharp corners.
5.The entire conductor is at the same potential and so the surface is an equipotential.
The potential difference ΔV
between two conductors charged to ±Q is proportional to the charge:
of the two conductors.
The permittivity constant or ε
A parallel-plate capacitor with plates of area A and separation d has a capacitance:
C = κε
is inserted between the plates of a capacitor, it's capacitance is:
Increased by a factor
of the material.
energy stored in a capacitor
2.This energy is stored in the electric field, which has energy density:
For a capacitor charged to ΔV
the potential at distance x from the negative plate is:
The electric field inside is:
1V = 1J/C
1 electron volt =
is the kinetic energy gained by an electron upon accelerating through a potential difference of 1V.