Equations
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information
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units
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F = k(q1q2 )/r2 |
vector: magnitude, direction, components (resultant) + forces represent repulsive forces between two charges |
N
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E = kQ/r2 |
vector: magnitude, direction, components (resultant) + fields represent fields around positive charges |
N/C
V/m
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where k = 9 x 109 N m2/C2 |
Coulomb's constant
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N m2/C2
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F = qE
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vector: magnitude, direction, components (resultant)
+ forces represents forces whose direction in the same direction as the field
line
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N
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Vabs = kQ/r
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scalar: magnitude only
+ equipotential surfaces surround positive charges |
J/C
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EPE = qΔVabs |
scalar: magnitude only
+ EPE signifies that the charge has gained electric potential energy |
J
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EPEsys = Σk (qiqj / rij)
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scalar: magnitude only
Remember that this is the SUM OF THE POTENTIAL ENERGY OF EACH PAIR of charges
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J
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Wdone by external agent = qΔV
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scalar: magnitude only
Remember that the absolute potential at infinity is defined to be zero.
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J
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Wdone by field = -ΔEPE
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scalar: magnitude only
Remember that + charges move to points of lower electric potential when moved along
electric field lines, therefore they lose EPE. Consequently, when the field
does positive work on a charge, (W = Fs cos θ where
θ = 0º) the charge loses EPE and gains KE
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J
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previous material:
kinematics equations
(accelerated motion)
R = vHt
net F = ma
W = Fs cos θ
KE = ½ mv2
conservation of energy
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Remember to use H | V charts when analyzing 2-dimensional motion
Remember your graph shapes for s vs t and
v vs t Remember that projectiles have a parabolic trajectory when they experience
accelerated motion in one dimension and constant velocity in another
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