# Ph-204 Chap 21

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1. The electric potential V is:
created by charges and exists at every point surrounding those charges.
2. When a charge q is brought near these charges:
• it acquires an electric potential energy
• Uelec = qV
• at a point where the other charges have created an electric potential V.
3. Energy is conserved for a charged particle in an electric potential:
• Kf + qVf = Ki + qVi
• or
• ΔK = -qΔV
4. 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.
5. The electrical potential of a point charge q is:
V=K(q/r)
6. For a 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.
7. What is C:
Capacitance.
8. The potential difference ΔVC between two conductors charged to ±Q is proportional to the charge:
• ΔVC = Q/C
• where C is the capacitance of the two conductors.
9. The permittivity constant or εο:
8.85x10-12C2/N⋅m2
10. A parallel-plate capacitor with plates of area A and separation d has a capacitance:
C = κεοA/d
11. When a dielectric is inserted between the plates of a capacitor, it's capacitance is:
Increased by a factor κ, the dielectric constant of the material.
12. 1.The energy stored in a capacitor is:
2.This energy is stored in the electric field, which has energy density:
• 1.UC= ½C(ΔVC)2
• 2.UE=½κεοE2
13. For a capacitor charged to ΔVC the potential at distance x from the negative plate is:
• V=x/dΔVC
• The electric field inside is:
• E=ΔVC/d
14. Electric potential:
1V = 1J/C
15. Electric field:
1V/m=1 N/C
16. Energy:
1 electron volt = 1eV = 1.60x10-19 J is the kinetic energy gained by an electron upon accelerating through a potential difference of 1V.
 Author: Allistermark ID: 201052 Card Set: Ph-204 Chap 21 Updated: 2013-02-17 04:30:14 Tags: Chapter 21 Electric Potential Energy Folders: Description: Electric Potential Energy and Electric Potential, Show Answers: