# Dipole (electrical) and Electric Field Concept

Hi all, I'm kind of confused right now about some concepts.

- Dipoles are essentially point charges of the same magnitude but different signs that are a certain distance away from each other, right?

-In my textbook, they were calculating a charged particle that is on the dipole axis. They got an a E that is in the direction of z (as opposed to x/y). Why is the direction of the electric field at the point P (on the dipole axis) z? The charges of the dipole and the charge at P are all on x, y plane, unless I misunderstood something.

-However, in earlier examples with charges on the same plane with other charges, the E they got was restricted in the x,y plane.

Why is this so? Am I missing something?

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dx
Homework Helper
Gold Member
If the dipole axis is in the direction of z, then the field at a point on the axis will also point along the z direction. You can understand this using the principle of superposition. Work out what the field due to each charge will be and add them (vector addition).

Doc Al
Mentor
The dipole axis is a line going through both charges. If that axis is the z-axis, then the field at some point along the z-axis will be parallel to the z-axis. On the other hand, the field at some point on the x-y plane that bisects the dipole (assume the dipole is at z = 0) will also be parallel to the z-axis.

(dx beat me too it!)

Never mind, I misunderstood what the textbook was saying, thanks for the input though.