EM Flashcards
1
Q
Gauge theory
A
Lagrangian is invariant under local transformations
in EM
general guage transforms are
A=A + grad(f)
V =V -df/dt
2
Q
Equation for B-magnetic field
A
Curl of A
A=vector potential
3
Q
Equation for electric field
A
minus gradient of the electric potential minus the partial time derivative of the vector potential
E= - Grad(V)-dA/dt
4
Q
Maxwell’s equations
A
div E = 4pirho – Gauss’s
div B= 0 –Gauss’s for magnetism
curl E = -(1/c )dB/dt —Maxwell faraday
curl B = (1/c)(4piJ+dE/dt) – ampere’s law
5
Q
Gauss’s theorem
A
integral over a surface = integral of divergence over a volume
6
Q
stokes theorem
A
integral over a closed path = integral of curl over a surface
7
Q
continuity equation
A
d(rho)/dt +div(J) =0
8
Q
charge and charge density
A
Q = int(rho dV)
9
Q
current and current density
A
I = int( J dS)
