# Homework Help: Electric Potential Graph

1. Feb 1, 2005

The electric potential along the x-axis (in kv) is plotted versus the value of x, (in meters). Evaluate the x-component of the electrical force (in Newtons)on a charge of 2.10 micro-C located on the x-axis at x=-3.6 m.

Ok I 'm doing Ex=-dV/dx. I get the slope to be (-7500 N/C) from doing -(5Kv-20kV)/(0m-2m). Then I am multiplying -7500N/C by the charge of 2.10 mC to get .01575 N and I need an answer in N so I thought this was right, and it's not lol. Help?

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2. Feb 1, 2005

### MathStudent

hmm... the graph isn't exactly linear in that interval, and those values don't look like they can be determined precisely just by looking at the graph ( no function is given for potential wrt x is there? ).
However checking your calculations, it looks like you multiplied -7500N/C by 2.10 micro coulombs (10^-6 C) . Micro has the symbol $\mu$
but in the problem, the charge is given in milli coulombs (10^-3 C ) so your answer might be off by a factor of 10^3.

Last edited: Feb 1, 2005