1
PHYSICS 4B EQUATION SHEET
12
12 12
2ˆ
kq q
r
Fr
Coulomb’s Law
q
F
E
Electric Field
rE ˆ
2
r
q
k
Electric Field due to a
point charge
rE ˆ
2
r
dq
k
Electric Field due to a
continuous charge
2k
Er
E-field due to infinite line
of charge
2o
E
E-field due to an infinite
plane of charge
o
E
E-field just outside a
conductor
EE dA
Electric Flux
enc
Eo
q
E dA
Gauss’s Law
p qd
Electric Dipole Moment
τpE
Torque on Electric Dipole
UpE
PE of electric dipole
B
BA
A
U
V V V d
qEs
Electric Potential
Difference
U qV
Electric Potential Energy
12
kq q
Ur
Electric Potential Energy
kq
Vr
Electric Potential due to a
point charge
dq
Vkr
Electric Potential due to an
extended body of charge
EV
Relation between V and E
Q
CV
Capacitance
oA
Cd
Capacitance for Parallel-
Plate Capacitor
12eq
C C C
Capacitors in Parallel
12
1 1 1
eq
C C C
Capacitors in Series
2
1
2oE
Energy Density in an
E-field
o
C kC
Capacitance with
Dielectric
o
E
Ek
E-field with Dielectric
2
1
2
U CV
Energy in a Capacitor
dQ
Idt
Electric Current
I
JA
Current Density
JE
Ohm’s Law
RA
Resistance
V IR
“Ohm’s Law”
1
Resistivity
12eq
R R R
Resistors in Series
12
1 1 1
eq
R R R
Resistors in Parallel
()
t
V
I t e
R
Current Charging
Capacitor
( ) (1 )
t
q t CV e
Charge Charging
Capacitor
RC
Time-Constant
qF v B
Magnetic Force on a
Moving Charge
IF L B
Magnetic Force on a
Current-Carrying
Conductor
b
a
IdF s B
Magnetic Force on a
Current-Carrying
Conductor
μτB
Torque on Current
Loop
μUB
Magnetic Potential
Energy
F qE qv B
Lorentz Force
HIB
Vnqt
Hall Voltage
