Problem 25.9

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Three point charges of equal charge are arranged on the corners of an equilateral triangle, as shown in the animation.  Each charge is measured in nC (nanocoulombs or 10^-9 C) and can be varied using the slider.  You can click-drag to read the value of the voltage at any point in the animation (position is given in meters, voltage is given in volts, and charge is given in nanocoulombs).  Restart.   

1. Find a formula for the voltage midway between the charges (indicated by the small black dot) as a function of the charges. 
2. Looking at the electric field vectors, where is the electric field zero?  Explain.
3. Is the voltage at that spot also zero?  If not, explain why you can have a zero electric field, but a nonzero voltage.

Problem authored by Chuck Bennett and Wolfgang Christian and modified by Anne J. Cox.
© 2004 by Prentice-Hall, Inc. A Pearson Company