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TWO Point Charges on the x-axis and an electric field graph

  • #1

Homework Statement



Two point charges qA and qB are located on the x-axis at x=a and x=b. The figure is a graph of Ex, the x-component of the electric field.
What are the signs of qA and qB?

Homework Equations



http://session.masteringphysics.com/problemAsset/1071455/4/29.EX31.jpg

The Attempt at a Solution




I feel like... since the graph is symmetrical, the two charges should be the same sign, eg, either both negative or both positive, but i do not know how to interpret the electric field graph! I dont understand how the electric field lines tell me anything, they are going neither towards or away from the point charges... i'm trying to think if the asymptotes mean anything but I just don't know where to begin?
 

Answers and Replies

  • #2
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if both charges were same .. field should have been 0 in between a and b ... which is not .. so i think that they are of opposite sign
 
  • #3
so are you saying that the electric field graph as shown in the figure is indicative of electric field strength? I still don't understand what the graph is indicating, what those lines stand for?
and if they were of opposite sign, and the graph is symmetrical, how would i go about deciding which charge, a or b, is positive or negative?
 

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