Finding complex power in AC circuit

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Discussion Overview

The discussion revolves around the calculation of complex power in an AC circuit, specifically focusing on the relationship between current, impedance, and the resulting power calculations. The scope includes conceptual understanding and technical reasoning related to AC circuit analysis.

Discussion Character

  • Technical explanation, Conceptual clarification, Homework-related

Main Points Raised

  • One participant presents a calculation for complex power using the formula i²z, resulting in a value of 1489.85 - j1152.74 W, but expresses uncertainty about its correctness.
  • Another participant questions whether the initial query is a homework problem.
  • A later reply clarifies that the query is not related to a homework problem but seeks to understand the concept of calculating complex power when given impedance and current.
  • One participant explains that the voltage can be expressed as V = I * Z, separating the real and imaginary components, and notes that the average power dissipated is calculated using I_{RMS}² * Re(Z).

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the initial calculation, and there is ongoing clarification regarding the concepts involved in calculating complex power.

Contextual Notes

There are unresolved aspects regarding the assumptions made in the calculations and the definitions of terms used, particularly in the context of AC circuit analysis.

Raghav Gupta
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In a branch I have to find complex power which is having current 19.41<-37.3 A and impedance 4+j3 Ω
What I used is i2z and I was getting 1489.85 - j1152.74 W.
This is wrong but I don't know how because by this site the answer was different
http://www.rapidtables.com/calc/electric/power-calculator.htm
Can someone tell me what is wrong going on?
 
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Is this a homework problem?
 
Chandra Prayaga said:
Is this a homework problem?
No the homework problem was something other. When I was doing it in middle this query araised. I just want to ask the concept that when impedance is given and current is given, the complex power should be Vi or i2z, isn't it?
 
The voltage is give as ## V = I * Z = I * Re(Z) + I * I am (Z) ##. The second term is 90 degrees out of phase with respect to current. The average power dissipated is then ##I_{RMS}^2 * Re(Z) ##
 

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