# Math Help - electric field

1. ## electric field

charges of 1micro coloumb 8 microcoloumb and 27 micro coloumb and so on are placed at x=1,2...10. then determine the electric field at origin

can you please tell me the answer

2. Originally Posted by prasum
charges of 1micro coloumb 8 microcoloumb and 27 micro coloumb and so on are placed at x=1,2...10. then determine the electric field at origin

can you please tell me the answer
That's not the way we work around here. With 147 posts, I'd have thought you'd have figured that out by now.

Follow forum rule # 11 and show some effort. What have you done so far? What ideas have you had?

3. i have supposed a test charge at origin and then used the principle of superimposition

4. And what did you get?

5. is this right or wrong

6. It's a perfectly good way to proceed. I'm asking what your result was.

7. 55

8. What are the units and direction?

9. units are micro coloumb/m^2 how will i find the direction

10. I see where your 55 comes from, and I agree there's a 55 in your answer. Shouldn't there also be a $1/(4\pi\varepsilon_{0})$ in your answer?

As for the direction, all the point charges contribute to the electric field in the same direction. Check this definition for the direction of the unit vector $\hat{\mathbf{r}}.$

The units of the electric field, after all the cancellations have taken place, is newtons per coulomb in the SI system.