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Name:  Venkatesh K.
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 2000-2001


Question:
Just as I say that resistance is caused by the obstruction to the motion of electrons in a resistor, what is the physical interpretation of inductance (i.e. why does an inductor oppose any sudden change in current through it)?


Replies:
Venkatesh,

Inductance is a magnetic property, actually a combination of magnetic and electric properties. Current flowing through a wire causes a magnetic field to circle around the wire. A CHANGING magnetic field creates an electric field around itself. With a straight wire, this has no significant effect.

If the wire is wrapped in a coil, however, inductance occurs. When current changes, magnetic field changes. The changing magnetic field through the center of the coil causes electric field that opposes the CHANGE of the current. A voltage is produced across the coil pushing opposite the change. An inductor will allow any size current to flow, so long as the current doesn't change. A slow change has very little effect. A fast change produces a quick change of the magnetic field, which produces a large voltage to oppose the change.

Scientists know that induction does happen. We know it is because changing magnetic fields produce electric fields. We do not, however, know WHY changing magnetic fields produce electric fields.

Dr. Ken Mellendorf
Illinois Central College



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