Question

There is a thin rod of length L. The top half of the rod has a charge +Q, and the bottom half of the rod has a charge -Q.

Evaluate the electric field E at a distance r = 7.40 cm if L = 7.30 cm and Q = 3.50 nC

Answer 1

First of all +Q and -Q would cancel, so the correct answer is zero. So i guess it doesn't matter that no info is given about the location of the point r from the rod.