EMEC - Greg

Definitions

Electromagnetism Units

Symbol	Units	Name	Definition
		Flux	The rate of transfer of energy (or another physical quantity) per unit area <ref> http://en.wiktionary.org/wiki/flux </ref>
${\overrightarrow {E}}$	${\frac {V}{M}}$	Electric Field Intensity	The space surrounding an electric charge. It will exert a force on other electrically charged objects.
${\overrightarrow {D}}$	${\frac {C}{M^{2}}}$	Electric Flux Density
${\overrightarrow {H}}$	${\frac {A}{M}}$	Magnetic Field Intensity
${\overrightarrow {B}}$	$T={\frac {W}{M^{2}}}$	Magnetic Flux Density

Analogies between Electric & Magnetic Circuits

Electric	Magnetic	Notes
$V=\int {\overrightarrow {E}}{\overrightarrow {dl}}$	${\overrightarrow {F}}=\int {\overrightarrow {H}}{\overrightarrow {dl}}$
$\sum _{n}V_{n}=0=\oint {\overrightarrow {E}}{\overrightarrow {dl}}$	$\oint {\overrightarrow {H}}{\overrightarrow {dl}}=Ni=\sum _{n}Hl+Ni=0$	Kirchoff's voltage law, Ampere's law
$\sum _{n}I_{n}=0=\oint _{S}{\overrightarrow {J}}{\overrightarrow {dS}}$	$\oint {\overrightarrow {B}}{\overrightarrow {dS}}=0$	Kirchoff's current law, The B-field has to go around in a loop
$\oint {\overrightarrow {J}}{\overrightarrow {dS}}=I$	$\int {\overrightarrow {B}}{\overrightarrow {dS}}=\Phi$	Magnetic flux, Phi
$R={\frac {V}{I}}$	${\mathfrak {R}}={\frac {F}{\Phi }}={\frac {Ni}{\Phi }}$	Reluctance
$I={\frac {V}{R}}=GV$ or ${\overrightarrow {J}}=\sigma {\overrightarrow {E}}$	${\overrightarrow {B}}=\mu H$	Assumes linearity - exceptions: Hysterisis loop, etc