18.7 Exercise 34

(a) Find the electric field at the center of the triangular configuration of charges in the figure, given that $q_{a} =+ 2 . \text{50} \text{nC}$, $q_{b} = - 8 . \text{00} \text{nC}$, and $q_{c} =+ 1 . \text{50} \text{nC}$. (b) Is there any combination of charges, other than $q_{a} = q_{b} = q_{c}$, that will produce a zero strength electric field at the center of the triangular configuration?