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I know that displacement current is produced in dielectric material due to dipole moment. I also know that displacement current is produced by time varying electric field (according to maxwell equation) so now why is this displacement current not produced in dielectric material with steady Electric field?

And also if the medium is free space is there any affect of time varying fields?

I am not sure if my question is correct. Please someone explain me the concept clearly , where I am missing?

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  • $\begingroup$ Are you confusing a displacement field for a displacement current, by any chance? It's an easy to make mistake and the terminology does not make it easy to keep the phenomenology apart. The displacement current does exist in vacuum without polarizable media, but we have to include polarization of matter into the case where polarizable matter is present, which always confuses the heck out of me, for sure. $\endgroup$ – CuriousOne Jan 5 '16 at 17:07
  • $\begingroup$ yes, Is this displacement field not responsible for displacement current? $\endgroup$ – sizzling_. Jan 6 '16 at 11:27
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A displacement field is produced by the polarization of a dielectric. A displacement current is produced by a time-varying electric field.

The two concepts are completely different. A displacement field does not cause displacement current, and a displacement current is not affected by displacement field.

There is no displacement current in a dielectric with a steady electric field because a displacement current is produced by a time-varying electric field, not a steady one. There is a displacement current in free space produced by a time-varying electric field because if there's a time-varying electric field, then there's a displacement current.

Although the two concepts are completely different, they do both have "displacement" in their name, which as CuriousOne mentioned is quite confusing. Furthermore, a displacement current isn't an actual current, with charges moving around and all that; it just has an associated magnetic field as if it were a real current. Hopefully that clears things up.

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