# Shared Flashcard Set

## Details

Ch 17 Electric Potential
includes equipotential lines, capactinace, dielectrics
29
Physics
02/09/2013

Term
 electrostatic force is a nonconsevative or a conservative force?
Definition
 conservative force
Term
 as particle accelerates from point a to point b is the potential energy decreasing or increasing? what about KE?
Definition
 potential energy is decreasing  KE is increasing by an equal amount
Term
 given a positive & negative plate +       - +     - +     - +    - +   - 1.where will the postive charge,q, have : the highest potential energy    2.where will the negative charge,q, have : the highest potential energy?
Definition
 1.at the positive plate 2. at the negative plate
Term
 what is Electric potential ?
Definition
 potential energy per unit charge
Term
 what are Equipotential Lines
Definition
 equipotential is a line or surface over which the potential is constant.
Term
 Electric field lines are _____ (direction)  to equipotentials.
Definition
 perpendicular
Term
 The surface of a conductor is an usually made up of
Definition
 equipotential.
Term
 what is an electron volt (eV) ?
Definition
 the energy gained by an electron moving through a potential difference of 1 volt.
Term
 potential vs electric field which is a scalar quantity, which  is a vector?
Definition
 potential: scalar electrical field: vector
Term
 The potential due to an electric dipole is equal to
Definition
 the sum of the potentials due to each charge, and can be calculated exactly
Term
 electric dipole def
Definition
 two equal point charges (Q )of opposite signs that are seperated by a distance l.
Term
 dipole moment  formula
Definition
 p = Ql Q=sum of point charges l= distance btwn them
Term
 what is capacitor?
Definition
 consists of two conductors that are close but not touching  fcn:the ability to store electric charge.
Term
 When a capacitor is connected to a battery, the charge on its plates is
Definition
 proportional to the voltage on the battery. (aka the emf of battery)
Term
 capacitancedoes not depend on
Definition
 voltage
Term
 capacitance (the ability to store electrical charge) is a fcn of
Definition
 the geometry and materials of the capacitor.
Term
 what is a dielectric?
Definition
 is an insulating  sheet of material placed bwtn the plates of a capacitor.
Term
 T or F: dielectrics do not breakdown, allwing electric flow as readily as air.
Definition
 True, high voltages can be applied without charge passing across the gap.
Term
 T or F: dielectrics allows the plates to placed farther apart, thus decreasing the captiance.
Definition
 False, dielectrics allow the plates to be placed together without touching, thus increasing the capactiance.
Term
 t or f: if a dielectric is used as an insulator then it can increase the  capactiance by a factor K
Definition
 true,  K is also known as dielectric constant
Term
 Concept question: An airfilled capacitor consisting of 2 parallel plates seperated by a distance,d, is connected to a battery of voltage V and acquires a charge, Q. Question: While is still connected to the battery, a slab of dielectric material with K=3 is inserted btwn the capacitor plates. Will the charge (Q) increase , decrease, or remain the same?
Definition
 Increase   recall the capacitor is still connected to the capacitor, so the voltage (V)  will continue to be  equal to the charge of the battery. Recall Q= CV where C is the capactiance , which increase by the use of  a dielectric.   Therefore MORE CHARGE (Q) will be pulled from the battery to the plates of the capacitor
Term
 Suppose the same airfilled capacitor mentioned in the other example, is charged (to Q )and then disconnected from the battery.  Next a dielectric is inserted btwn the plates, Will Q,C,or V change?
Definition
 Q (charge):  remains the same the capacitor is isolated (disconnected) so there is nowhere for the charge to go.   C(capacitance): increases because dielectric is inserted   V(voltage): decreases Q= CV   V= Q/C if the denominator increases while numerator remains the same (aka being divided by even MORE PEOPLE ) the volatge will decrease.
Term
 Dielectric strength def
Definition
 is the maximum field a dielectric can experience without breaking down.
Term
 How do molecules in an dielectric arrange themselves?
Definition
 The molecules in a dielectric tend to become oriented in a way that reduces the external field.(this is referring to the plates) aka reduces charge repulsions
Term
 why is it important that the molecules  in the dielectric materaial reduce repulsions with the respect to the plates?
Definition
 electric field within the dielectric is less than it would be in air, allowing more charge to be stored for the same potential.
Term
 energy density def
Definition
 as the energy per unit volume & is the same no matter the origin of the electric field
Term
 an example of Storage of Electric Energy
Definition
 Heart defibrillators use electric discharge to “jump-start” the heart, and can save lives
Term
 For capacitors in SERIES , all capacitors are equal in?
Definition
 charge   (each capacitor has to store the same amout of charge).
Term
 For capacitors in PARALLEL , all capacitors are equal in?
Definition
 voltage
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