Field due to a Uniformly Charged Rod

Problem: A thin rod of length 2 m is placed along the x axis with one end 30 cm from the origin. It is charged uniformly with 12 microcoulombs. Find the electric field at the origin.

Solution: We will use symbols and substitute the numbers at the end. See the figure at the right for the definitions of the symbols.

I will drop the vector notation, since the direction is entirely in the negative x as shown, and just work with the magnitude of dE.