PHYS-2210 Study Guide - Final Guide: Equipotential, Kinematics, Interactive Voice Response
2 Apr 2016
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Remember that the electric field inside a (charged or uncharged) conductor was exactly equal to zero. If charges are moving, however, there must be a field to produce the coulomb force needed to accelerate these free charges. One way we can set up an electric field inside a conductor is to connect it to a battery as illustrated below. The field above in the cylindrical conductor will accelerate free electrons to the left, opposite the field. The collective motion of many free electrons in this conductor is known as electric current. Below we see free electrons moving to the left in the electric field created by the battery through a cross-sectional circular surface of area. The electrons have an average velocity called the drift velocity vd. We define average electric current in this conductor as the amount of charge that flows through the cross-sectional area per unit time:
