Electricity and Magnetism

• Electric Fields


  -The region or space surrounding a charged particle or a time varying magnetic field.

  -Can also cause magnetic field

  -Measured in N/C or V/m
• Magnetic Fields

  – The region or space surrounding a magnetic material or a conductor carrying an electric current.

  – Its strength is measured in A/m

  – It can cause electric field.
• 4 of Maxwell's Equation

  Gauss Law for electrostatics

  Gauss Law for magnetism

  Faraday's Law

  Ampere's Law (with Maxwell's correction)
• GAUSS LAW for electrostatics.


  explains the relationship between electric charges in a closed surface and the electric flux crossing that surface.
• GAUSS LAW for magnetism


  explains that there is no magnetic charge (instead, a dipole).
• FARADAYʼS LAW


  ‒ explains how a time-varying magnetic field produces an electric field.
• AMPEREʼS LAW (with MAXWELLʼS CORRECTION)


  explains that magnetic fields can be generated in two ways: By electrical current and by changing electric field.
• Electricity 


  is the phenomenon associated with the presence and motion of electrons and other charged particles.
• Electrostatics

  • Deals with the phenomena due to the attractions or repulsions of electric charges that are not moving.
• -1.6x10&-19 C

  1 Electron Charge
• +1.6x10^-19 C

  1 Proton charge
• Coulombʼs FIRST LAW of Electrostatics

  – The size of the force of attraction or repulsion between two charges is directly proportional to the value of each charge.
• Coulomb's SECOND LAW of Electrostatics

  The size of the force varies inversely as the square of the distance between two charges.
• Electric Flux

  These are lines that stream away symmetrically from a point charge; it is also called as “DISPLACEMENT” or DISPLACEMENT FLUX”.
• Flux Density (D)

  The number of flux (or lines) per unit area with unit C/m2.
• Gaussʼs Law


  The electric flux passing through any closed surface is equal to the total charge enclosed by that surface.
• Divergence


  The divergence of vector flux density A is the OUTFLOW OF FLUX from a small closed surface per unit volume as the volume approaches zero.
• The Divergence Theorem


  • States that the outward flux of a vector field through a closed surface is equal to the volume integral of the divergence over the region inside the surface.
• Magnetism

  The property of a device or material to attract bodies of iron and other magnetic material or magnets.
• BOHR MAGNETON

  The strength of a magnetic moment of an electron (μB) due to electron spin.
• Weber Theory


  assumes that all magnetic substances are composed of tiny molecular magnets
• Domain theory


  -based on electro spin theory.
• Magnetic Field


  the space surrounding a magnet where magnetic forces act.
• Lines of Force


  lines that are used to represent the force existing in the area surrounding a magnet called magnetic Lines of Force.
• Magnetic Flux 


  -total number of magnetic lines of force leaving or entering the pole of magnet.
• Maxwell

  • cgs unit of magnetic flux
  • 1 Maxwell = one magnetic field Line
• Weber


  -SI unit of magnetic flux

  -1 Weber equals 1x10^8 lines or maxwell
• Magnetic Flux Density


  The Number of magnetic field Lines per unit area of section perpendicular to the direction of Flux.
• GAUSS


  -A CGS unit of magnetic flux Density

  -it has a unit of one line or Maxwell per square centimeter
• Tesla


  SI unit of Magnetic Flux density

  has a unit of 1 weber per square meter
• Permeability


  ability to accept, allow, or setup a magnetic field is described by this.
• BH Curve


  depicts the ability of a material to accept, allow, or set-up a magnetic field as it is subjected to a magnetizing force.
• Magnetic Hysteresis


  delayed reaction of the magnetization of a ferromagnetic material, with the change of the magnetizing force.
• Ferromagnetic Materials


  materials with relative permeability very much greater than 1.
• Paramagnetic materials


  relative permeability slightly greater than 1
• Diamagnetic Material


  relative permeability slightly less than 1.
• Curie Temperature


  temperature above Tc where ferromagnetic or ferrimagnetic materials become paramagnetic.
• Electromagnets


  are type of magnets where its magnetic field intensity is directly proportional to the current flowing through a coil with a number of turns.
• Magnetic Circuits


  a closed path to which a magnetic field, represented as lines of magnetic flux is confined.
• Magnetomotive force


  force that tends to setup the magnetic flux.

  Force is produced due to applied electric current in the coil of N turns.