for this coulomb's law question, why can't i solve by splitting e into Ex and Ey and then combining given Ey is zero? I get an answer 10^-30 instead of 10^-10.

Question

The solution here says to figure it out by using cos theta as a factor, but I don't understand why I cannot just break it up into components?

Figure shows two charge particles on an x acis -q on the -x side with a magnitude -3.20*10^-19 at x=-3.0m and a positive q and x=3.0 m on the x axis. Point P is located at 4.0 m on the y axis. What are teh magnitude nd direction of the net electric field at point P?

Answer 1

Remember that the electric field equation is E = kq/r², which is different from the Coulomb force equation that is F_E = k|Qq|/r².

Answer 2

You can solve it by breaking E-field into Ex and Ey. We know Ey will be 0. And the Ex from both particles will have the same magnitude and direction. Then we just do the calculation and get Ex in the order of magnitude of 10^-10.