Physics 232 Exam 2

Coulomb’s Law

F=kqq/r²

Coulomb’s constant

K=1/4πε=8.99E9

Electric Force/Field

F=qE

Electric Potential Energy/Voltage

ΔU=qΔV

Closed surface electric field (Gauss’ Law)

∯E*da=Q(enclosed)/ε

Voltage/Electric Field

ΔV=-∫E*ds

Electric field/Voltage

E=-dV/ds

Point charge electric field

E=kq/r²

Electric field set of point charges

E=ΣEi

Electric field infinite plane of charge/parallel plate capacitor

E=η/2ε, E(paralell plates)=η/ε (away if +, toward if -)

Electric Potential Energy for 2 point charges

U=kqq/r

Voltage for a point charge

V=kq/r

Total voltage for a set of point charges

V=ΣV

Voltage across parallel plate capacitor

V=Ed

Voltage/Capacitance

ΔV=Q/C

Potential Energy/Capacitance/Voltage

U=(1/2)CV²

Capacitance in parallel

C=C1+C2+C3+…

Capacitance in series

1/C=1/C1+1/C2+1/C3+…

Dipole moment

p=qs (- to +)

Torque

τ=pxE

Potential Energy/dipole/field

U=-p*E

Series vs Parallel

Series: all have same charge, Parallel: all have same voltage