Electromagnetic Fields Flashcards
Permiability ε
The ability of a substance to support the formation of an electromagnetic field within itself
Magnetic Moment
Magnetic quantity that describes both the force and torque that a magnetic field will exert on an electric current
Premativity ε0
The ability of a resist to support the formation of an electromagnetic field within itself
Representing electromagnetic fields
Always in a vector field in continuous Structure
Electron behavior in a field
Moves from the positive end, orthogonal to the surface, to the negative end, at an angle orthogonal to the surface
Electromagnetic Field
A feedback loop between the electric field and the magnetic field, generated by the electric charges
Electromagnetic feedback loop
1) Electrical charges produce electrical and magnetic fields
2) The electrical field interacts with the magnetic field (opposite to the electrical field)
3) Field acts on particles in the surrounding space, creating forcefields (electrical force: same direction as electrical field, magnetic force: perpendicular to the magnetic field)
4) Particles begin to move, creating a current
5) Particle movement generates more fields
Electromagnetic Field vector components
Electrical: E(x,y,z,f)
Magnetic: B(x,y,z,f)
Isolated electrical field
Electrostatic field, never with a time component
Isolated magnetic field
Magnetostatic field, never with a time component
Maxwell’s equations
1) Gauss’ Law
2) Gauss’ Law for magnetism
3) Faraday’s Law
4) Ampere-Maxwell’s Law
Gauss’ Law
Electric flux of an object is equal to its charge divided by its permeability, or the surface integral of the electromagnetic field with respect to area
Φ=Q/ε=∫∫E⊙dA
Meaning the dot-product of the gradient and the electrostatic field is charge density over material permeability
∇⊙E=p/ε
Gauss’ Law for Magnetism
The dot-product of the gradient and the magnetostatic field is zero
∇⊙B=0
∫∫E⊙dA=0
Faraday’s Law
Curl of an electrostatic field is the negative differential equation for magnetostatic B over t
∇xE=-∂B/∂t
Ampere-Maxwell’s Law
Curl of a magnetostatic field is the sum of the current-density magnet-constant product and the (differential E with t)(magnet constant)(permeability constant)
∇xE=μJ+εμ(∂E/∂t)
Review the study portion for vector calculus
Do it now
Electrical displacement
D=μE+P
P=Polarization
E=Field strength
ε0=Permativity
Function for the electrostatic field
E(x,y,z)=F(x,y,z)/q
Electrical potential (voltage)
Φ=U/q
Force Vector field
F=-∇U
Negative gradient of the energy vector field
Electrostatic vector field
E=-∇Φ
Negative gradient of the voltage potential vector field
Electrostatic field strength
|E|=-ΔΦ/d
Voltage difference between the plates, divided by the distance between them
Electrical displacement vector field
D(r)=εE(r)
Energy density
u=(1/2)ε0|E|^2
Electrodynamic Lorenz force vector
Electromagnetic foce on a charged particle at a point
F=qE+(qv x B)
q=particle charge
E=electrostatic vector at that point
v=velocity of charge
B=magnetostatic vector at that point
Electrostatic Force vector field
F=qE
Charge density
Coulombs per unit of volume
Polarization density
Molecular Dipole moment (always as a vector) per unit of Volume
Right hand rule
Give a thumbs up…
If current flows up through your thumb,
Then the magnetic field generated travels in the direction indicated by your fingers
System Capasitance
Ability of the system to store energy in its electric feild
System Inductance
The ability of a system to store energy in its magnetic field
Uniform Electromagnetic Force
Fe=q|E|
Product of charge and magnetude of the electromagnetic field
Given as culoumbs per meter=newtons
Non-uniform Electromagnetic force
Fe=(910^9)q1q2/r^2
Basically, its the law for gravitational force, but with charged particles
Uniform Electric Field Strength
E=F/qt
Electromagnetic force over the test charge
Test charge (qt)
The charge the moves in the system
Stationary charge (qs)
The charge that results in acceleration in the test charge
Non-uniform electric field strength
E=k*qs/r^2
