Problem about rc and lr circuits

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Homework Help Overview

The discussion revolves around the phase difference between voltage and current in RC and LR circuits, particularly questioning why this phase difference is not equal to 90 degrees as expected. The original poster shares experimental results and seeks to understand the impact of resistance on phase differences in both capacitors and inductors.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the reasons behind the observed phase differences, questioning the assumptions of ideal components versus real-world behavior. They discuss the effects of resistance in both capacitors and inductors on phase shifts.

Discussion Status

The discussion is ongoing, with participants sharing insights about the nature of real inductors and capacitors, including the effects of resistance and stray capacitance. There is no explicit consensus, but various interpretations of the experimental results are being explored.

Contextual Notes

The original poster's results indicate a phase difference that deviates from the expected 90 degrees, prompting questions about the ideal versus real behavior of circuit components. The discussion highlights the complexities introduced by resistance in practical scenarios.

kimduncanaimar
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i hv done an experiment
but why the phase differencr between the voltage and current for both LR and RC circuits are not equal to 90?
moreover,how would a resisiance of a resistor affect the phase difference
between voltage and currentin capacitor?:cry:
at last,how would a resistor affect the phase difference between voltage and current in inductor?
 
Last edited:
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The voltage and current in a capacitor or in an inductor are 90 degrees out of phase.
In an RC or LR circuit the voltage and current are out of phase by the angle of the total impedance Z = R + jX.
 
SGT said:
The voltage and current in a capacitor or in an inductor are 90 degrees out of phase.
In an RC or LR circuit the voltage and current are out of phase by the angle of the total impedance Z = R + jX.

but from my result,it doesn't equal to degree of 90:cry:
 
kimduncanaimar said:
but from my result,it doesn't equal to degree of 90:cry:

There is no pure inductance or capacitance.
A real inductor is made of a wound wire, so it has a resistance associated and this causes the phase shift to be different from 90 degrees.
There is also a stray capacitance between turns of the coil, that contributes to alter the phase.
In a capacitor the phenomenon is less important, but it has also a resistance and an inductance associated.
 

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