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25 Cards in this Set
- Front
- Back
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charge
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a property that gives rise to attraction or repulsion
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charge is...
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conserved- chare is not created or destroyed, we move charge
quantized- comes in fixed amounts |
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conductors
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metals...electrons are loosely held in place and are free to move between atoms(get current from)
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Insulator
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wood, plastic, rubber... electrons are held tightly in place- they dont move between atoms
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electricity wants to be in...
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equillibrium
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ways to charge objects
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1. friction- rubbing objects together, moving electrons from 1 object to another
2. Conduction- charging by contact, touching a charged object to an uncharged object 3. induction- charging by proximity |
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Coulomb's law
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Fe= kqq/r2
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coplanar steps for solving the problem
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1. FBD
2. Magnitudes of forces (F31)(F32) 3. Components (x and y) 4. tangent theta |
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Electric Field
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defines the way a positive charge would go or field lines start on positive and end on negative
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Electric Current
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(I) change in charge over change of time
I = Q/t= C/s= Amperes |
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Conventional current
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the way a positive charge would go
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Flow of energy
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- the energy flow from the higher temp to the lower temp
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thermal equillibrium
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the flow ceases when both ends reach the same temp
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flow of charge
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charges flow when they are pushed
- when flow is negative, electrons are flowing - when flow is positive, protons are flowing -there must be a difference in potential in order for it flow from one end to another |
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Electric current
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flow of electric charge
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Ohm's law
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V=IR
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drift velocity
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electrons drifting in a certain direction
- as wire heats up, resistance goes up |
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cross sectional area, length and drift velocity relationships
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1. as cross section increases, the resistance decreases
2. length and resistance are proportional 3. resistivity and resistance are proportional |
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wire differences and relationships
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wire gets long- resistance gets big
wire gets fat- resistance gets small |
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superconductivity
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zero resistance, cooler wire, easier for electrons to get thhrough (low temp)
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hot wire and cold wire
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hot wire- electron moves faster= drift velocity is slow
cold wire- electrons slower- drift velocity faster |
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series circuit
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defined by having 1 path
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wat to do to find Req in a series circuit
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add up all the resistors (measured in Ohms)
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parallel circuits
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more then one path
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wat to do to find Req in a parallel circuit
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take the numbers and put a one over them and then get the answer and do x-1 on calculator to get R
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