(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Hi, here is the problem I'm having trouble with:

Three charges Q1, Q2, and Q3, each equal to 6.4 × 10–19 C, are in a straight line. The distance between neighboring charges is 60 nm. Find the magnitude of the electric field at P, which is 80 nm from Q2 on a line at right angles to the line between Q1 and Q3

2. Relevant equations

E = kQ/r^{2}

3. The attempt at a solution

The correct answer is 1.9 x 10^{6}N/C, but I cannot figure out how to arrive at that answer.

I started by first finding the magnitude of the electric field from each charge

E1 = kQ1/r^{2}= (8.99 x 10^{9}Nm^{2}/C^{2})(6.4 x 10^{-19}C) / (100 x 10^{-9}m)^{2}= 575360 N/C

E2 = kQ2/r^{2}= (8.99 x 10^{9}Nm^{2}/C^{2})(6.4 x 10^{-19}C) / (80 x 10^{-9}m)^{2}= 899000 N/C

E3 = kQ3/r^{2}= (8.99 x 10^{9}Nm^{2}/C^{2})(6.4 x 10^{-19}C) / (100 x 10^{-9}m)^{2}= 575360 N/C

Then I tried splitting those into the x and y components

E_{x}= 0, since E1_{x}and E3_{x}cancel each other out and there is no x component of E2

E1_{y}= 575360sin[itex]\theta[/itex] = 345216 N/C

E3_{y}would also equal this

E2_{y}= 899000 N/C

E_{y}= 1589432

so to find the magnitude of the resultant vector...

E = [itex]\sqrt{}[/itex](E_{x}^{2}+ E_{y}^{2})

E = [itex]\sqrt{}[/itex](0^{2}+ 1589432^{2}) = 1589432

E = 1.59 x 10^{6}

So what am I doing wrong here? Any help would be appreciated

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# Homework Help: Finding the magnitude of the electric field from 3 charges at a point P

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