Plotting the Electric Potential in Excel

We now have a grid of (x,y) values and are ready to calculate the electric potential at these points.

• In cell B2 enter the formula:
  
  
  =0.2/SQRT(B$1^2+$A2^2)
  
  
  Better yet just copy and paste it.
• This is the formula for the electric potential due to a particle with charge 2.224 X 10^-11 C. The charge doesn't necessarily correspond to anything real; it is simply chosen so that kq=0.2 N m²/C.
• Note that B$1 replaces x in the formula kq/(x²+y²)^1/2.
• And $A2 replaces y in it.
• All of the calculations we do here will be in the xy-plane, i.e. the z coordinate is zero for all of them.
• The placement of the dollar signs is crucial. Please be careful.
• When a formula is copied, the dollar sign tells Excel that you do not want to change the part of the cell reference that follows. Thus when the formula is copied, the B in B$1 may change but the 1 won't (i.e. we are always referring to a cell in the first row).
• Similarly, when the formula is copied the 2 in $A2 may change but the A won't (i.e. we are always referring to a cell in the first column).

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