PhysicsLAB Review
Electrostatics Point Charges Review

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Equations information units
F = k(q1q2 )/r2 vector: magnitude, direction, components (resultant)
+ forces represent repulsive forces between two charges
E = kQ/r2 vector: magnitude, direction, components (resultant)
+ fields represent fields around positive charges
where k = 9 x 109 N m2/C2 Coulomb's constant N m2/C2
F = qE vector: magnitude, direction, components (resultant)
+ forces represents forces whose direction in the same direction as the field line
Vabs = kQ/r scalar: magnitude only
+ equipotential surfaces surround positive charges
EPE = qΔVabs scalar: magnitude only
+ EPE signifies that the charge has gained electric potential energy
EPEsys = Σk (qiqj / rij) scalar: magnitude only
Remember that this is the SUM OF THE POTENTIAL ENERGY OF EACH PAIR of charges
Wdone by external agent = qΔV scalar: magnitude only
Remember that the absolute potential at infinity is defined to be zero.
Wdone by field = -ΔEPE 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
previous material:
   kinematics equations
      (accelerated motion)
   R = vHt
   net F = ma
   W = Fs cos θ
   KE = ½ mv2
   conservation of energy

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

General Information

charging methods:(basic electrostatics)
     by conduction: temporary vs residual charges
     charging by induction: temporary vs residual charges
     electrification by friction
positively charged: loss of electrons (|e| = 1.6 x 10-19 C)
inverse square relationships (Coulmb's force and E fields for point charges)
inverse relationships (voltage for point charges)
charges flow from one location to another because of a difference in potential
charge configurations comparing net E and net V at a common point
radial electric fields (point charges)
direction of field lines: positive charge, negative charge, similar charges, unlike charges
uniform electric fields (parallel plates)
battery notation: long line positive, short line negative
field strength: density of field lines or closeness of equipotential surfaces
conductor vs insulator
Faraday's Ice Pail Experiment
conducting shells

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Catharine H. Colwell
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