Question

We have a charge q = -0.6 x 10^-6 C at origin. And a vector r = (0 m, -5 m, 0 m). Find the electric field E(r) as a vector expressed in terms of i j and k.

Ok so far I got E(r) = k (0.6e-6)/(5)^2 = 216 N/C. But this is not a vector, how do I express this in terms of I j and K?

Answer 1

E=kq/r^2=kq*(r as a vector)/r(magnitude)^3

E=k(-6E-6)((0,-5,0)/(0,125,0)=(0,6k/25 E-6,0)
In this problem it is simple to realize E points toward the origin, (216N/C j) ( I did not check the 216), or (0,216,0)

Answer 2

Could you explain to me why E points towards the origin? The vector r points in the negative direction anyway (away from origin). so -j