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• Fundamental forces of nature

  • Gravitational
  • Electromagnetic
  • Strong
  • Weak
• Electricity


  Phenomenon associated with stationary or moving particles
• Electricity (Greek word)

  "elektra" - Amber
• Electricity is an "attraction" phenomena
• Electricity (William Gilbert)


  • Coined "electricus" meaning "like amber"
  • Observed the activity of electric attraction, electric force and magnetic bodies
• William Gilbert is considered the Father of Electrical Studies
• Electric charge


  • An inherent physical property of certain subatomic particles that is responsible for electrical and magnetic phenomena
  • SI Unit: Coulomb (C)
• Charged particles


  • Proton (Charge: +1.6x10^-19 C)
  • Neutron (Charge: 0 C)
  • Electron (Charge: -1.6x10^-19 C)
• Net charge of an atom = 0 C
• Properties of electrical charges

  • Unlike charges attract, like charges repel
  • Electric charge is always conserved
  • Charge comes in discrete packets that are integral multiples of the basic electric charge e=1.6x10^-19 C
  • The force between two charged particles is proportional to the inverse square of the distance between them
• Classification of electrical charge

  • Conductors (Materials that permit the easy movement of electrical charge)
  • Insulators (Materials that do not permit the easy movement of electrical charge)
  • Semiconductors (Materials with electrical properties somewhere between insulators and conductors)
• Coulomb's law


  The electric force has the following properties: 1) It is directed along a line joining the two particles and is inversely proportional to the square of the separation distance r, between them. 2) It is proportional to the product of the magnitudes of the charges, q1 and q2, of the two particles. 3) It is attractive if the charges are of opposite sign and repulsive if the charges have the same sign.
• Electrical permittivity


  How much a given substance "permits" electric field lines to pass through them
• Absolute permittivity of free space


  The measure of permittivity in a vacuum or free space. It measures the resistance encountered when forming an electric field in a vacuum.
• Relative permittivity


  The permittivity of a given material relative to that of the permittivity of a vacuum.
• Electric field


  An electric property associated with each point in space when charge is present in any form. E = Electric Field Strength or Electric Field Intensity (N/C or V/m), F = Force on a Charged Object (N), q_0 = Test Charge (C), Q = Source Charge (C), d = distance of Test Charge from Source Charge (m), ϵ_0 = Absolute Permittivity (8.854 x 10^-12 F/m or C^2/N∙m^2)
• Electric field lines


  Imaginary lines, the tangent to which, at any point, gives the direction of the electric field intensity
• Gauss' law


  The summation of the normal component of the electric field displacement E(normal) over any closed surface is directly proportional to electric charge within the surface. Electric flux is the total number of field lines passing through a given cross sectional area perpendicular to the direction of Electric field lines.
• Qualitative statement of Gauss' law


  • Charges outside the surface do not give a net electric flux through the surface. 2) The net electric flux is directly proportional to the net amount of charge enclosed within the surface but is otherwise independent of the size of the closed surface. 3) Whether there is a net outward or inward electric flux through a closed surface depends on the sign of the enclosed charge.
• Electric field density


  The number of field lines that crosses a unit area or the lines of force per unit area. D = Electric Flux Density (C/m^2), Ψ = Gaussian Sum or Electric Flux, A = Area
• Electric potential energy


  The energy that is needed to move a charge against an electric field.
• Work done by force

  Coulomb's law of attraction
• Electric potential


  The potential energy per unit charge between two locations in an electric field. Denoted as Volts (V).
• Electric potential difference (voltage)


  The difference of Electric Potential between two locations in an electric field.
• Capacitance


  The ability of a component or circuit to collect and store energy in the form of an electrical charge.
• Capacitor


  A device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other.
• Dielectrics


  Materials characterized by their ability to resist the flow of electric current. They serve as insulating mediums between conductive surfaces, such as the plates of a capacitor. When subjected to an electric field, dielectric materials polarize, meaning their electric charges become aligned in a way that reduces the overall electric field within the material. This property allows dielectrics to store electrical energy in the form of electric potential energy, thus increasing the capacitance of a capacitor.
• Practical types of capacitors

  • Variable Air Capacitor
  • Mica Capacitor
  • Paper Capacitor
  • Ceramic Capacitor
  • Plastic Capacitor