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?
I see where your 55 comes from, and I agree there's a 55 in your answer. Shouldn't there also be a $\displaystyle 1/(4\pi\varepsilon_{0})$ 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 $\displaystyle \hat{\mathbf{r}}.$
The units of the electric field, after all the cancellations have taken place, is newtons per coulomb in the SI system.