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## Main Question or Discussion Point

First assumption: the change of magnetic flux in time outside a conductor is zero.

Last semester in circuit analysis we treated circuits with sinusoidal voltage variation as steady state circuits while using the phasor notation. But now that i know electrodynamics i begin to doubt my concepts that were built in circuit analysis. For sinusoidal variation of voltage the electric field through the conductor will also vary sinusoidally which means that there will be a changing magnetic field enclosed by the circuit. What assumption here is needed to lead to the assumption that the change in magnetic flux outside a conductor is zero? Is it that the surface area of the circuit is too small? But that is not satisfactory...

Second assumption: the change of charge in time inside conducting elements is zero.

This means that displacement current is zero, right?

Source: http://en.m.wikipedia.org/wiki/Lumped_element_model

Last semester in circuit analysis we treated circuits with sinusoidal voltage variation as steady state circuits while using the phasor notation. But now that i know electrodynamics i begin to doubt my concepts that were built in circuit analysis. For sinusoidal variation of voltage the electric field through the conductor will also vary sinusoidally which means that there will be a changing magnetic field enclosed by the circuit. What assumption here is needed to lead to the assumption that the change in magnetic flux outside a conductor is zero? Is it that the surface area of the circuit is too small? But that is not satisfactory...

Second assumption: the change of charge in time inside conducting elements is zero.

This means that displacement current is zero, right?

Source: http://en.m.wikipedia.org/wiki/Lumped_element_model

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