Module 2 : Electrostatics
Lecture 10 : Potential Energy of a System of Charges
 
  The electric field strength at the point P may be found by finding the slope of the potential at the point P. If $\Delta x$is the distance between two equipotential curves close to P,
 
\begin{displaymath}E = -\frac{\Delta \phi}{\Delta x}\end{displaymath}
  where $\Delta\phi$ is the difference between the two equipotential curves near P.
  Example 17
  Example 18
  Exercise 1
   
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