Term
| Define Electric Potential Energy (U) |
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Definition
EPE=qEd, these are conservative forces
energy charge has in an electric field |
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Term
| Define Electric Potential (V) |
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Definition
| EP=EPE/q, this is the position in electric field (no charge needs to be present) |
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Term
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Definition
| C=Q/V, a measure of the amount of electrical energy stored (or separated) for a given electric potential. |
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Term
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Definition
| An electrical insulator that can be polarized by an applied electric field |
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Term
| Describe the physics of capacitors in parallel and series |
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Definition
In parallel, cap's add like r's in series (Ceq=C1+C2...)
In series, cap's add like r's in parallel (Ceq=C1C2/C1+C2 OR 1/Ceq=1/C1+1/C2...) |
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Term
| How are electric field and electric potential related mathematically? |
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Definition
EP=Ed=EPE/q=V
--> V=kq/r
---->E=kq/r^2
*Electric field lines are perpindicular to V lines |
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Term
| Discuss the physics of a wire connected to a battery. |
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Definition
Electrons move down a wire just like water moves down a pipe--in case of water, GPE is greater at one side, so it moves down in the pipe in the direction away from the high PE
In the case of the wire, EPE must also be higher at one side, so electrons travel away from the higher PE (one side of the battery is some amount of V and the other is 0V) |
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Term
| Electric potential of a point charge |
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Definition
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Term
| Electric potential of an electric field |
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Definition
constant-- abs(E)= ∆V/∆X
or ∆V=-E∆X |
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Term
| How much work is required to assemble two protons 1cm apart? |
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Definition
U=qV
U=q2V1
U=q2(kq1/r12)
U=kq1q2/r12
*Just need q for a proton* |
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Term
| Capacitance of a parallel plate capacitor |
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Definition
C=єoA/d єo=8.85X10^-12 A=m^2 d=m
A=(pi)r^2 |
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Term
| How much energy is stored in a capacitor? |
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Definition
| U=1/2CV^2 must be conncected to a battery, and energy stored is used in short, quick bursts |
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Term
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Definition
| Intermittent windshield wipers, flash bulb camera, timing circuits, tune frequent radios, filters in power supplies |
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Term
| What do capacitors do in circuits? |
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Definition
| In circuits, cap's charge up and provide delay time because of quick bursts of energy. When a circuit is switched off cap's slowly discharge |
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Term
| What do resistors do in circuits? |
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Definition
| Resistors limit current, so when combined with cap's, they cause a slower charging up of the cap. |
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Term
| Potential inside of a conductor |
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Definition
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Term
| Three advantages of placing a dielectric between the plates of a cap |
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Definition
(1) capacitance increases by a factor of K(kappa) C=Kє0A/d
(2)provides mechanical support so that the plates don't touch
(3)it increases the Vmax and allows it to store more energy(you can put more volts across the cap) |
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Term
| Electric field inside a conductor |
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Definition
| Zero (because of sheilding) |
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Term
| Why does electric potential decrease inside of a capacitor when a dielectric is placed between the plates? |
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Definition
| The electric field of the capactior decreases when the dielectric is introduced because is creates its own, smaller electric field. If EP=Ed, and E decreases and d is constant, then EP decreases. |
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Term
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Definition
electron volt--it is a non-mks unit for energy that 1eV=1.6x10^-19J
the kinetic energy that an electron gains by going through a potential difference of 1V. |
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Term
| Potential difference in uniform electric field |
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Definition
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Term
| Why can an electric potential energy function be defined for the electric force? |
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Definition
| Because electric force is conservative force, and conservatice forces define EPE function |
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Term
| Resistors in series and parallel |
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Definition
In series, R's Voltage adds (Vtotal=V1+V2...)
In parallel, R's have an equal voltage (V1=V2=Vtotal...) |
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