[Physics] Is a phase difference of 180 degree possible between EMF and current

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While studying alternating currents I could read and observe through an oscilloscope that there can be phase difference between EMF and current. But, is a phase difference of 180 degrees possible in a series LCR circuit?

Best Answer

No, a phase difference of 180º between applied voltage and current is not possible in a standard LCR circuit.

However, for reference, it is possible to construct electronic circuits that mimic negative resistance or negative impedance. In the case of negative resistance, $R = \dfrac{-V}{I}$. Here is a wikipedia article about it.

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This will, for a voltage sine wave produce a 180º phase shift in the current. These types of circuit can use inductors and capacitors and without going through all the possibilities there is probably a way of adding L, C and Rs around an op-amp to achieve it too.