Question

An electric dipole is placed on the y-axis with +Q at y=0 and -Q at y=-d, as shown in the figure. What is the magnitude of the electric field at a point P located at x=d on the x-axis?

Answer 1

We superimpose the two Efields as follows:

where I have used sin 45° = cos 45° = 1/ √2  . Solving for the magnitude yields,