This simulation visualizes the integration used to calculate the electric field for a uniformly charged rod. Move the red point to change where the electric field is to be calculated. Change the charge per length of the rod using the slider. The thin red rectangle represents one "slice" out of the integral. This rectangle can be moved along the rod. The total electric field in the x and y-directions is calculated by summing (integrating) the contributions from the "slice" at each position along the rod.

What changes when you drag the thin red rectangle?

By watching the electric field vector, can you find a location where the y-component of the electric field is zero?

By watching the graphs to the right, can you find a location where the x-component of the electric field is zero?

cos, sin, and were all left inside the integral in the calculation on the bottom left of the page. Why aren't these things constant?