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63 Cards in this Set
- Front
- Back
Charge is quantized meaning it can't be split up, what is the formula for finding the charge on atom?
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q = (+/-(e))*n
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What is the value for the two constants e and k
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K= 9e9
e= 1.6e-19 |
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When the columb equation has a positive value, do the charges attract or repel?
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They repel
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How many charges are required when making an electric field
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One charge (source charge)
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If you have a positive electric field, then what direction is the electric field and what is the equation for the electric field?
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The equation for electric field is
E=K*(Q)/r^2 The E means the source charge that created the electric field is positive and the electric field will point away from the charge |
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When looking electric field lines, where is the electric field the strongest?
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Where the lines converge together
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What is the equation to find the force created by an electric field on a charge
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F=qE
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What changes the acceleration of a particle in an electric field
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The change in electric field
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In electric field equations if you have a negative force, what does this tell you about the direction of the force in relevance to the electric field
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The force points opposite the electric field
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What is a scalar quantity in electrostatics and what is different between electric field and electric potential
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Electric potential and the electric potential is the same everywhere at the same distance because this is scalar, while electric field is not the same at a r because it involves direction
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What does the sign on the electric potential correspond to and what is the equation
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The equation is Potential = k(Q/r)
The sign corresponds to a negative or positive charge |
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What are the units for electric potential?
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The units are volts (J/C)
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What is the equation for finding the change in electric potential energy
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PE = q*(change in potential difference)
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How can one find the kinetic energy and potential energy in an charge
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The work equals = -Delta PE
Delta KE= -Delta PE |
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If I say a charge spontaneously acceleartes what does this mean
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The charge is gaining kinetic energy
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What is 1ev
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This simply means that an electron * 1 potential difference so.... 1eV=1.6e-19
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The superposition principle is used in electric potential but what is different when comparing to the other electric forces
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You just add up the electric potetential there is no vectors
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Why can't we use W=Fd in electric and what work equation is used to move one charge and which is used to move total charge?
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Because force isn't constant
Total charge= W=.5QV One charge=potential difference*charge |
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Are equipotentials always perpendicular or parrallell to electric field lines,
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perpendicular
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The eqaution for work in electric is corresponding to what
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The work equals negative potential energy
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What is an mnemonic for statements involving electric potential
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Protons-heavy
Electrons-light Rocks fall (lower potential) Helium rises(higher potential) |
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What is current
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The net movement of charge. I=Q/t
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What is drift velocity
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The movement of electrons. If THERE IS drift velocity there is a current
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What creates current
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Net movement of charge
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What is the formula for resistivity
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R=resistivity*(L/A)
A-cross sectional area |
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Does resistivity increase or decrease with temperature
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Increase
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How do you add resistors in parralel and in series. And what is important about adding resistors in parallel,
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In series you add R1+R2...and so fourth
In a parrallel you add (R1*R2)/(R1+R2) In a PARALLEL YOU CAN ONLY ADD TWO RESISTORS AT A TIME |
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What is the convention for saying the flow of a current
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The flow of a current is always the direction that positive charges will flow
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Often the question is what remains constant in series and parrallel, describe how current and voltage are changed or the same in either one
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Series= Current the same, V may change if resistors change
Parrallel-V the same, I may change if resistors change |
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What are the two kirchoff laws
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The voltage that came from the battery, when you sum the whole circuit will equal this value
The current passing the battery, will be the sum of the current pass through all indv. resistors in the combination.- page 252 |
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What is the formula for power dissapated by the resistor and power supplied by the battery equation and how can they relate
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P=IV-battery
P=I^2*R-for each resistor THe sum of the resistor will equal the power by the battery |
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What is the equation to find energy in a circuit
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Remember-power=energy/time
Energy = time*power |
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What is the equation to find terminal voltage
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V=EMF-Ir= if battery supplies circuit
V=emf+Ir- if circuit is supplying current to the battery |
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When does the current stop with a capcitor
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When the capacitor's voltage equals the voltage of the battery
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What is the equation for charge on the capacitor
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Q=V*C
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What affecs capacitance
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Distance between the parrallel plates and the size of the plates
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What is the equation for capacitance
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C = e*(A/d)
eo-8.85e-12 |
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What is very important to remember about capacitance
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Capacitance is a constant the only thing that changes capacitance is the area of the plate and the distance between the plates
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What is the equation to find electric field on parallel plate with capacitor
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V=Ed
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Is there work used when moving electrons to a positive charge
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Yes, the work done by the voltage source. Work against the electric field of the capacitor
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What is the formula for finding Potential energy in a capacitor
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PE=.5*Q*V
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Describe what happens as one discharges a capacitor
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The capacitor will first discharge quickly and then will level off slowly
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What does the precesnce of a dielectric do to the capacitance
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It will increase
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What happens when a dielectric is placed in between a capacitor plates after the battery as been removed?
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The Q will remain constant!!!!
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What happens to the voltage as a capacitor is being charged with a battery and a dielectric is placed in between?
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The V will remain constant
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Explain dielectric breakdown
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The dielectric increases the maximum of an electric field so electrons can't go throgh (air) to the positive plate. The dielectric prevents polarization.
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What are the equations for Vrms and Irms
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Vrms= Vmax/(2)^1/2
Irms = Imax/(2)^.5 |
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How are magnetic fields created?
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They are created by moving electric charges
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What is the equation to determine the magnetic force that a charge will feel
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F=velocity of charge*charge*B
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How does one find the magnitude of force of a magnetic field
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F= abs(q)*v*Bsin(theta)
The angle is between the v and B |
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Is the magnetic field force perpendicular or parallel to the v AND magnetic field lines
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Both are perpendicular to force
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Describe how to use the right hand rule
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USE YOur left hand for negative charges
Thumb is velocity Fb is your palm Fingers are B |
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Do magnetic forces do work
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No, because always perpendicular to the velocity of charge and this means they can't change kinetic energy
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What can magnetic forces change speed or direction
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Direction
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How do you find the radius of of the circular path of a proton, (the centripetal force)
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F= mv^2/r
qvB=mv^2/r |
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When a wire creates a magnetic field, what makes the magnetic field stronger?
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Being closer to the wire and increasing the current
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In a solenoid, where is the magnetic field the greatest
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In the middle, center of axis. Line through the bullseye
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How does magnetic field correspond in a solenoid
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B is proportional to I* (N/L)
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What equation can show how magnetic field is related to I and r in a wire
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B is proportional to I/r
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What is the units for Tesla
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Tesla equals N/A*m
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What is dependant only on shape, size and material, V, I or R
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R
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Besides the potential energy equation= 1/2QV, what is another eqation to determine energy through a capacitor
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.5CV^2
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Besides the E= kq/r^2, what is another equation to find electric field?
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E= Volts/meter = 1 V=1J/C, SO 1 V/m = 1N/C
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