EMEC - Greg

Definitions

Electromagnetism Units

Symbol	Units	Name	Definition
		Flux	A scalar value. The rate of transfer of energy (or another physical quantity) per unit area. <ref> Wiktionary - Flux </ref>
${\overrightarrow {E}}$	${\frac {V}{M}}$	Electric field (intensity/strength)	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/displacement field)	The amount of electric flux in a unit area perpendicular to the direction of electric field
${\overrightarrow {H}}$	${\frac {A}{M}}$	Magnetic field (intensity/strength)	A magnetic field is a vector field which surrounds magnets and electric currents, and is detected by the force it exerts on moving electric charges and on magnetic materials. <ref> Magnetic field </ref>
${\overrightarrow {B}}$	$T={\frac {W}{M^{2}}}$	Magnetic (flux density/induction)	The amount of magnetic flux in a unit area perpendicular to the direction of magnetic flow <ref> Magnetic flux density </ref>

Electric field lines <ref> Electric field lines</ref>

Electric flux density <ref> Electric flux density </ref>

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

References

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