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Phase in LCR circuits

  1. Nov 14, 2013 #1

    BMW

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    In an LCR circuit (circuit with inductor, capacitor and resistor), are the following statements always true?

    The capacitor voltage always lags the resistor voltage by a phase difference of 90°.
    The inductor voltage always leads the resistor voltage by a phase difference of 90°.
    The current is always in phase with the resistor voltage.

    Thanks.
     
    Last edited: Nov 14, 2013
  2. jcsd
  3. Nov 15, 2013 #2
    It depends on how you have connected them... series / parallel / R in series with parallel combination of L and C, C in parallel with series combination of L and R, or any other combination you can think of...

    This is only true for Series RLC circuits.

    For other circuits, if you have to analyse them, you should go by your basics. When connected in series, current through the components that are in series will be same (same magnitude and phase) and components in parallel will have same voltages across them (again, same magnitude and phase)...

    So making changes to your sentences:
    The capacitor voltage always lags the capacitor current by 90 degrees.
    The inductor voltage always leads the inductor current by 90 degrees.
    The resistor voltage and the current through will always be in phase with each other.

    Keeping these in mind, you analyse the circuit.
     
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