ELECTROSTATIC POTENTIAL AND CAPACITANCE Flashcards
WORK DONE
W = F X D
ELECTROSTATIC POTENTIAL ENERGY
U = KQq/ r
ELECTROSTATIC POTENTIAL DIFFERENCE
🔺️ U = Up - Ur = Wrp
ELECTROSTATIC POTENTIAL
Vp - Vr = Up - Ur / q
V = Kq/r
POTENTIAL DIPOLE
- AXIAL
- EQUITORIAL
Vp = kpcos o/ r^2
1. kq/r^2 - a^2
kq/r^2 ( a is negligible)
- 0
EQUITPOTENTIAL SURFACE WORK DONE
0
ELECTRIC FIELD AND POTENTIAL
E = -dv/dr
EQUIPOTENTIAL SURFACE ARE PERPENDICULAR TO
ELECTRIC FIELD
POTENTIAL ENERGY OF A SYSTEM OF 2 CHARGES
U = KQ1Q2/R12
- E.F INSIDE CONDUCTOR
- at surface
- what charge is in interior of conductor
- Electrostatic potential throughout volume
- 0
- normal to all points
E = SIGMA/eo - no excess charge
- constant
Dielectric in an external field
E = Eo - Ep
sigma p = sigma o ( 1- 1/k)
Eo = external field Ep = polarizied field E = net field
Polarization
P= Qp d
p = sigma p Ad
p (vect) = sigma p
p = xo E (vec)
(Xo = (K-1)eo
K=1+Lambda
Capacitance
Q=CV
Electrical displacement
D= eoE+p D= eokE
SPHERICAL CAPACITOR
C = R/K
Concentric Spherical Capacitor
C = ab/ k (b-a)
Cylindrical Capacitor
C = l/2k (ln b/a)
Parallel Plate Capacitor
C = A eo/ d
Dielectric on Capacitor (completely filled)
C = K Aeo / d C = KCo
Combination of capacitor
- Series
- Parallel
- 1/C = 1/C1 + 1/C2 ……
2. C = C1 + C2….
Energy stored in the capacitor
U= Q^2/ 2C U = 1/2 CV^2 U = 1/2 QV
energy density
u = 1/2 eo E^2