Question

Given is a line of charge of uniform linear density. A charge +q is distributed uniformly between y = 0 and y = a and charge –q is distributed uniformly between y = 0 and y = -a.

 

Explain how the direction of the resultant electric field at point P can be obtained. Represent using a vector diagram.

Answer 1

The x-components of E₁ and E₂, due to two equidistant points on either side of O, cancel each other. 

The resultant electric field is due to the superposition of the y-components of E₁ and E₂. 

The direction of the net electric field is along the negative y-axis. 

This is true for all pairs of equidistant points on either side of O.