Electromagnetism

electrodynamics banner 5Electromagnetism is a branch of physics that deals with the motion of electric currents and magnetic fields.  The force of that electromagnetic field exerts on ellectrically charged particles.  The electromagnetic force acting between the electrically charged protons and electrons inside atoms and between atoms are essentially responsible for gluing togeather all ordinary matter.

 

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Nomenclature & Symbols

 

  • \( \phi \), \(\; V \)  -  absolute electric potential
  • \( \epsilon \)  -  absolute permittivity
  • \( \left( P \right) \)  -  AC average power
  • \( Z \)  -  AC electrical impedance
  • \( l_o \)  -  AC peak current
  • \( V_o \)  -  AC peak voltage
  • \( C \)  -  capacitance
  • \( V_c \)  -  capacitive load voltage
  • \( X_c \)  -  capacitive reactance
  • \( G \)  -  conductance
  • \( J_c \)  -  convection current density
  • \( T_c \)  -  capacitive time constant
  • \( J_d \)  -  displacement current density
  • \( Q \)  -  electric charge
  • \( I \)  -  electric current
  • \( J \)  -  electric current density
  • \( P \)  -  electric dipole moment
  • \( D \)  -  electric displacement field
  • \( \phi_d \)  -  electric displacement flux
  • \( E \)  -  electric field
  • \( \phi_e \)  -  electric flux
  • \( P \)  -  electric power
  • \(EM\)  -  electromagnetic energy
  • \( EMF \)  -  electromagnetic field
  • \( Hz \), \(\; f \)  -  frequency
  • \( Y \)  -  gyromagnetic ratio
  • \( Z \)  -  impedance
  • \( L \), \(\; H \)  -  inductance
  • \( V_l \)  -  inductive load voltage
  • \( X_l \)  -  inductive reactance
  • \( T_l \)  -  inductive time constant
  • \( H \)  -  intensity of magnetic field
  • \( E \)  -  intensity of electric field
  • \(c\)  -  light
  • \(F\)  -  Lorentz force
  • \( g \), \(\; p \)  -  magnetic charge
  • \( B \)  -  magnetic field
  • \( \phi_b \)  -  magnetic flux
  • \(F_m\)  -  magnetic force between parallel conductors
  • \( T \)  -  magnetic induction
  • \( \mu \)  -  magnetic permeability
  • \( A \)  -  magnetic potential
  • \( M \)  -  magnetization
  • \( MMF \)  -  magnetomotive force
  • \( M \)  -  mutual inductance
  • \( Op Amp \)  -  operational amplifier
  • \( \delta \), \(\; \phi \)  -  phase constant
  • \( P \)  -  polarization density
  • \( TCR \), \(\; RTC \)  -  temperature coefficient of resistance
  • \( R \), \(\; \Omega\)  -  resistance
  • \( V_r \)  -  resistive load voltage
  • \( L \)  -  self inductance
  • \( VCR \)  -  voltage coefficient of resistance
  • \( VD \)  -  voltage drop

 

Electromagnetism Glossary

A

  • Air gap  -  Distance between two surfaces that engage in magnetic action.
  • Anisotropic  -  A type of magnet which is able to cary a higher amount of magnetisation.

B

C

  • Centimeter. Grams, Second (C.G.S.)  -  Also called gaussian units.   A system of measurement used mostly in magnetism.
  • Closed circuit condition  -  Exists when the external flux path of a permanent magnet is confined within high permability material.
  • Coercive force  -  The opposing magnetic intensity that must be applied to a magnetized material to remove the residual magnetism.
  • Coercivity  -  The resistance of a magnetic material to demagnetization.
  • Coulomb's law  -  The magnitude of the electrostatic force between two electric charges.
  • Curie temperature  -  When a material fails to be magnetic.
  • Current  -  The rate of flow of electricity in a circuit, measured in amperes.

D

  • Demagnetized  -  A material condition where a ringing AC field has reduced the remanent induction to or near wero.
  • Diamagnetism element  -  A type of magnetism with a very weak magnetic field that will repelled when in the presence of another magnetic field.

E

  • Electric field  -  An invisible space around a charged particle where an electric force is exerted on other charged particles.
  • Electrical generator  -  Converts mechanical energy to electrical energy.
  • Electricity  -  A build-up of energy or flow of electrons.
  • Electromagnetic energy  -  A form of energy travels through space as waves.

  • Energy  -  It is never created or destroyed First Law of Thermodynamics, but it can be transferred from one object to another.

F

  • Faraday's law of induction  -  States that whenever a conductor is placed in a varying magnetic field, an electromotive force is introduced.
  • Ferrite  -  A range of ceramic materials which all have magnetic ability.
  • Ferromagnetism element  -  A type of magnetism that forms a strong magnetic field and remains magnetized after the presence of another magnetic field has been removed.
  • Ferrous metal  -  Mostly contain iron.  Since they contain small amounts of metals or added elements they are magnetic and corrode, something non-ferrous metals do not.
  • Field  -  An invisible space around a charged particle where an electric force is exerted on other charged particles.
  • Flux  -  The number of magnetic lines of force.
  • Flux density  -  The number of lines of magnetism in each square centimeter of pole area.

G

  • Gauss  -  Unit of measure of the magnetic induction.
  • Gaussmeter  -  A device that measures magnetic flux.
  • Generator  -  A mechanical device that produces electrical energy from mechanical energy.
  • Gilbert  -  Unit of measure of magneto motive force.

H

  • Impedance  -  The total effects of a circuit that opposes the flow of an ac current consisting of capacitance, inductance, and resistance.
  • Inductance  -  The measure of an electric conductor or circuit by which an electromotive force is induced in it.
  • Induction  -  Magnetic flux per unit area of a section normal to the direction of flux.
  • Inductor  -  An energy storage device which stores energy in the form of a magnetic field.
  • Irreversible loss  -  Correspondsto the irreversible changes that take place when a magnet is demagnetized partially or completely because of exposure to high or low temperatures. or because of other factors such as external demagnetization fields.
  • Insulator  -  Prevents the free flow of electrons, and therefore does not let current flow through them.
  • Isotropic  -  A magnet without a preferred direction of magnetization.

J

  • Joule’s law  -  Is about the amount of heat (energy) delivered to something.

K

  • Keeper  -  A type of steel which protects the magnetic area around a type of magnet, and is often used when a magnet is being transported, or stored.

L

  • Leakage flux  -  Does not follow the intended magnetic circuit path.
  • Light  -  The electromagnetic spectrum describes light as a wave which has a particular wave length.

M

  • Magnet  -  An object made of certain materials which create a magnetic field.
  • Magnetic circuit  -  The combination of magnet, permeable flux carriers and air gaps through or around which the magnetic flux path passes.
  • Magnetic conditioner  -  A piece of equipment which demagnetises magnets in a slow and controlled manner.
  • Magnetic constant  -  Also called vacuum permability, and magnetic vacuum permability, a physical constant.
  • Magnetic energy  -  The energy within a magnetic field.
  • Magnetic field  -  Magnetic fields never cross, never start or stop, where the field is strongest, lines bunch togeather and can be seen clearly seen in the real world.
  • Magnetic flux  -  The number of magnetic field lines passing through a given closed surface.
  • Magnetic force between parallel conductors  -  Each wire creates a magnetic field around the wire.  The force between the two wires is related to the current of the wires and the distance between the wires.
  • Magnetic path  -  The route magnetic flux follows in a magnetic circuit.
  • Magnetic permeability  -  The ability of a material to produce a magnetic field, that is to concentrate the magnetic flux lines and thus to increase the value of magnetic induction.
  • Magnetic pole  -  An area where the lines of flux are concentrated.
  • Magnetic switch  -  Depending on the switch configuration for on and off, the switch is activated when the magnetic field is detected.
  • Magnetite  -  A black igneous, non-containing mineral with magnetic properties.
  • Maxwell  -  Unit of measure of magnetic flux.
  • Motor  -  Converts the electric energy to mechanical energy.
  • Mu-metal  -  A magnet which is made of nickel and iron primarily.
  • Multipole  -  A magnet which has in excess of two poles.

N

  • North pole  -  A magnetic pole of a magnet which is attached to a geogtaphic north pole if the earth.

O

  • Oersted  -  Unit of measure of the magnetization field.
  • Ohm's Law  -  The relationships between power \((P)\), voltage \((V)\), current \((I)\), and resistance \((R)\).
  • Open magnetic circuit  -  A circuit where a portion of the magnetic flux path is closed by air.

P

  • Paramagnetism element  -  A type of magnetism with a very weak magnetic field that will only happen when in the presence of another magnetic field.
  • Permeability  -  The extent to which a material is able to acquire magnetization in a magnetic field.
  • Polarity  -  A particular pole at a particular location of a permanent magnet.
  • Pole  -  An area where the lines of flux are concentrated.
  • Power  -  The rate of doing work and is measured by the amount of foot pounds of work done in a particular unit of time.

Q

R

  • Reluctance  -  A measure of the relative resistance of a material to the passage of flux.
  • Residual magnetism  -  The magnetism remaining in a substance after the magnetizing force has been removed.
  • Resistance  -  The ability to resist or prevent the flow of current. In order to overcome the resistance and get the current to flow a higher voltage will be required.
  • Resistor  -  Resist the flow of electricity.
  • Return path  -  Conduction elements in a magnetic circuit which provides a low reluctance path for a magnetic flux.
  • Right-hand rule  -  When current is flowing through a wire, the magnetic field rotates around the wire.  The direction of the current determines the direction of the magnetic field.

S

  • Search coil  -  A wire coil which makes up part of a fluxmeter, acting as a transducer.
  • South pole  -  A magnetic pole of a magnet which is attached to a geogtaphic south pole if the earth.
  • Static electricity  -  The build up of an electric charge on the surface of an object.
  • Stefan-Boltzmann law  -  Describes the power radiated from a black body, an ideal black surface that absorbs all radiant energy falling on it, in terms of temperature.
  • Surface field  -  The magnetic field strength at the surface of the magnet as measured by a gauss meter.
  • Switch  -  A device that opens and closes electrical circuit.

T

  • Temperature coefficient  -  The change in magnetic properties depending on temperature change.
  • Temperature stabilization  -  After manufacture, many types of hard and soft magnetic materials can be thermally cycled to make them less sensitive to subsequent temperature extremes.
  • Temporary magnet  -  A magnet that is made of a material that does not allow it to hold its magnetism permanently.
  • Tesia  -  Unit of measure of the magnetic flux density.
  • Thermal demagnetization  -  When a magnet is exposed to too much heat and it becomes demagnetised and therefore damaged.
  • Transducer  -  A voltage output device used for convert energy to another form.
  • Translucent  -  The material properties permitting the passage of light but diffusing it so that objects beyond cannot be clearly distinguished.
  • Transparent  -  The material properties of allowing light to pass through without a large scattering of light.
  • Transformer  -  A device that uses electromagnetism to convert one current to another current.

U

V

  • Vane  -  A piece of equipment which works as a target, a blocking between the magnetic field between sensor and the actual magnet itself. 
  • Volt  -  A unit of electrical pressure.  One volt is the amount of pressure that will cause one ampere of current in one ohm of resistance.
  • Voltage drop  -  The electricity between the meter and where it is be used.  It is basically impossible to have no voltage loss.

W

  • Weber  -  Unit of measure of the total magnetic flux.

X

Y

Z

 

 

Display #
Title
Faraday's Law of Induction
Light
Lightning Strike Distance
Lorentz Force
Magnetic Field

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