The discussion centers on the representation of RMS current as a phasor in AC circuits. Participants clarify that while RMS current describes an effective value, it can be associated with a phasor's magnitude, particularly in inductive circuits where current lags behind voltage due to reactance. The RMS value serves as a scaling factor for AC voltages and currents, maintaining the angular relationships between these quantities. Understanding the context and notation in textbooks is crucial for interpreting these concepts accurately.
PREREQUISITESElectrical engineering students, circuit designers, and professionals working with AC circuits who need to understand the relationship between RMS values and phasor representation.
I'm sorry I mean RMS currect, i'd edited the title and yeah I mean AC circuitdrvrm said:In which type of circuits you have encountered complex voltages...
i think in AC circuits the elements may not dissipate energy but act as storage devices and are related by phase difference, there in the analysis the instant voltages may be complex.
What I'm asking is RMS currect. I know that voltage and currect in AC circuit can be phasor, but why RMS current, which descibe a effective value, can be a phasor? It wouldn't change its value as the time is passing right?Zheng_ said:I
I'm sorry I mean complexcurrect, i'd edited the title and yeah I mean AC circuit
Zheng_ said:What I'm asking is RMS currect. I know that voltage and currect in AC circuit can be complex number, but why RMS current, which descibe a effective value, can be a phasor?
Ok thanksdrvrm said:the phase angle contains z the reactance which is complex
Suppose we have an inductive circuit, and here the voltage and current waves are not in-phase. Whenever a changing voltage is applied to an inductive coil, a “back” e.m.f. is produced by the coil due to its self-inductance. This self-inductance opposes and limits any changes to the current flowing in the coil.Further the effect of this back e.m.f. is that the current wave form reaches its peak value some time after that of the voltage. The current always “lags” behind the voltage .
But..one of the question in my homework let that I rms = 2∠10°?nasu said:But who said that the RMS value of the current is a phasor? You represent the variable quantities (current, voltage) by phasors.
The RMS value is just this, a value. Of course, you can take the magnitude of the phasor representing the current equal to the RMS value.
Same as the magnitude of the velocity vector is equal to the speed. This does not make speed a vector.
Ok thanks. I will go and read through my textbook.nasu said:That may be but it's hard to say what they mean without context. It may be just a notation to say that the magnitude of the phasor is equal to the RMS value and has a phase angle of 10 degrees.
The conventions for notations depend on the specific textbook. Read the chapter about phasors and pay attention to the meanings of the notations.
This tells you the current is i(t) = 2√2⋅sin(ωt+10°)Zheng_ said:But..one of the question in my homework let that I rms = 2∠10°?