Key Equations

Coulomb’s law

F = \frac{k q_{1} q_{2}}{r^{2}}

electric field	$\vec{E} = \frac{\vec{F}}{q_{test}}$
magnitude of electric field of point charge	$E = \frac{k \| Q \|}{r^{2}}$

change in electric potential energy for a charge that moves in a constant electric field	$Δ U_{E} = - q E (x_{f} - x_{i})$
electric potential energy of a charge a distance r from a point charge or sphere of uniform charge	$U_{E} = \frac{k Q q}{r}$
definition of electric potential	$V = \frac{U_{E}}{q}$
change in electric potential for a charge that moves in a constant electric field	$Δ V = - E (x_{f} - x_{i})$
electric potential of a charge a distance r from a point charge or sphere of uniform charge	$V = \frac{k Q}{r}$

capacitance	$C = \frac{Q}{V}$
energy stored in a capacitor	$U_{E} = \frac{1}{2} C V^{2}$
capacitance of a parallel-plate capacitor	$C = κ ε_{0} \frac{A}{d}$

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