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Why Power is Zero (0), in Pure Inductive, Pure Capacitive or a circuit in which Current and Voltage are 90 Degree out of phase?


Why Power is Zero (0), in Pure Inductive, Pure Capacitive or a circuit in which Current and Voltage are 90 Degree out of phase?

1.  Why Power in a circuit is Zero (0), in which Current and Voltage are 90 Degree out of phase?

If Current and Voltage are 90 Degree Out of Phase, Then The Power (P) will be zero. The reason is that,
We know that Power in AC Circuit
P= V I Cos φ
if angle between current and Voltage are 90 ( φ = 90) Degree. then
Power P = V I Cos ( 90) = 0
[ Note that Cos (90) = 0]
So if you put Cos 90 = 0→Then Power will be Zero (In pure Inductive circuit)

2.  Why Power in pure Inductive Circuit is Zero (0).
We know that in Pure inductive circuit, current is lagging by 90 degree from voltage ( in other words, Voltage is leading 90 Degree from current) i.e the pahse difference between current and voltage is 90 degree.
So  If Current and Voltage are 90 Degree Out of Phase, Then The Power (P) will be zero. The reason is that,
We know that Power in AC Circuit
P= V I Cos φ
if angle between current and Voltage are 90 ( φ = 90) Degree. then
Power P = V I Cos ( 90) = 0
[ Note that Cos (90) = 0]
So if you put Cos 90 = 0→Then Power will be Zero (In pure Inductive circuit)

                                                             Click image to enlarge


3.  Why Power in pure Capacitive Circuit is Zero (0)?
We know that in Pure capacitive circuit, current is leading by 90 degree from voltage ( in other words, Voltage is lagging 90 Degree from current) i.e the phase difference between current and voltage is 90 degree.
So  If Current and Voltage are 90 Degree Out of Phase, Then The Power (P) will be zero. The reason is that,
We know that Power in AC Circuit
P= V I Cos φ
if angle between current and Voltage are 90 ( φ = 90) Degree. then
Power P = V I Cos ( 90) = 0
[ Note that Cos (90) = 0]
So if you put Cos 90 = 0→Then Power will be Zero (In pure capacitive circuit)

                                                              Click image to enlarge

7 comments:

  1. Anonymous07:28

    what is difference between capicitance(C) and capacitor reactances(Xc)????
    plz ans

    ReplyDelete
    Replies
    1. Capacitance = the ability of a body to store an electrical charge
      C = Q/V
      and
      Capacitive reactance = an opposition to the change of voltage across an element.
      its a type of resistance in AC circuit.
      Xc = XC= 1/2πfC

      Delete
  2. please ans me we say capictor is use for improve power factor but the prove is reciprocal

    ReplyDelete
  3. please ans me we say capictor is use for improve power factor but the prove is reciprocal

    ReplyDelete
    Replies
    1. Wait for the upcoming Post as " How to improve the Power factor". Thanks

      Delete
  4. thank you. very useful

    ReplyDelete