Fundamentals of Electrical Engineering

Electrostatics

Paramjeet Singh Jamwal
B.Tech, EEE, College Of Engineering Roorkee
  • The Branch of Engineering which deals with the static charges is called electrostatics.
  • It is generally used while designing and studying lightening rods and capacitors.
  • When particular body is rubbed with another body, electric charge is produced.
  • Electric field strength or electric intensity


E = F/Q1 (in Newton/Coulomb)

 

 

  • The total number of lines of force emanating from a certain charge is called electric flux. Electric flux paths emanates from +ve electric charges and terminates on equal & opposite -ve charges. Electric flux Ψ is measured in coulomb.
  • εE is called electric flux density or displacement, designated by symbol D. It is measured at right angles to the direction of electric field in coulomb per square per meter.
  • The practical unit of Potential is Volts. In the SI system, Joule/coulomb or watt/ampere.
  • Potential gradient is defined as the rate of change of potentials with distance. potential gradient is equal to electrical intensity in magnitude but with negative sign.


g = dV/dx

 

 

  • Any two metal plates between which an electric field can be maintained constitutes a capacitor. Charge Q on each plate is directly proportional to potential difference between two plates. Capacitor or Condenser (ε is permittivity). Some important type of capacitors are mica capacitor, paper capacitor, ceramic capacitor and electrolyte capacitor.
  • The work done in bringing a charge dq to the plate of capacitor is given by

 

dw = v dq
  • Charging current 


i = C dv/dt

 

 

  • Time Constant of charging circuit may be defined as the time taken for the voltage across the capacitor to rise to 0.632 of its final value.


Basic Electrical Engineering

 

 

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