I was wondering if a material existed which opposed applied electric fields, analogously to a diamagnetic material, which opposes magnetic fields. So the flow of charge would be against the field, rather than toward the field. In other words, instead of electrons flowing or atoms polarizing towards a positive electric field, they move away from it and towards the negative, like a diamagnetic material aligning itself against the magnetic field. Maybe a big stretch, but I was wondering if that existed in any form.

Edit: Maybe I was unclear in my description of opposing electric fields. In a dielectric, the atoms and molecules polarize so that the negatively charged parts face the positively charged electrodes, and vice-versa. What I would be looking for would be the opposite of a dielectric. Would a negative permittivity material be an example of that?


1 Answer 1


If charge flows opposite the direction of the applied field, you have a material with negative resistivity. No such material exists.

However, it is possible to build a circuit that, within a limited range of applied voltage, delivers an opposing current (i.e. a negative resistance circuit). Such a circuit must necessarily include active devices and have a power source of some kind (i.e. it delivers power back to the input source rather than absorbing power from it).

It is also possible to build a circuit or device that has a negative differential resistance. That is, although the overall current flows in the usual direction associated with the applied voltage, a small increase in applied voltage produces a decrease in the current, or vice versa. Such devices don't necessarily require a second power source. Examples include tunnel diodes and Gunn diodes. The input of a DC-DC switching regulator circuit with a fixed load also exhibits negative differential resistance.


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