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Phasor diagrams for AC circuits







Phasor diagram

  • Phasor diagrams are diagram representing alternating current and voltage of same frequency as vectors or phasors with the phase angle between them
  • Phasors are the arrows rotating in the anti-clockwise direction i.e. they are rotating vectors but they represents scalar quantities
  • Thus a sinusoidal alternating current and voltage can be represented by anticlockwise rotating vectors if they satisfy following conditions
  • Length of the vector must be equal to the peak value of alternating voltage or current
  • Vector representing alternating current and voltage would be at horizontal position at the instant when alternating quantity is zero
  • In certain circuits when current reaches its maximum value after emf becomes maximum then current is said to lag behind emf
  • When current reaches its maximum value before emf reaches its maximum then current is said to lead the emf
  • Figure below shows the current lagging behind the emf by 900


    Phasor diagrams








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