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Electric Field of a dipole

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Homework Statement


A dipole consists of two charges +q and -q, held apart by a rod of length s, as shown in the diagram. If q = 4 nC and s = 2 mm, what is the magnitude of the electric field due to the dipole at location A, a distance d = 5 cm from the dipole?

The diagram shows point A being on axis with the dipole.

Homework Equations



The formula for on axis is 2qs/4piE*r^3, where E is the permittivity of vacuum

The Attempt at a Solution



So to solve this first I converted all units

q = 4nC = 4e-9C
s = 2mm = .002m
d = 5cm = .05m

Then I plug in the values into the formula

2*4e-9C*.002m/4pi*8.85e-12*.05m = 2.88N/C
But that seems to be the wrong answer can someone please tell me what I'm doing wrong
and also is it true that the field perpendicular to the dipole is just half of what it would be if it was on axis. If that's true than the field 5cm perpendicular to the dipole should be just half of what I come up with, in this case 1.44N/C.

Thank You for your help
 

Answers and Replies

  • #2
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Oh I think I figured out where I went wrong I forgot to cube d,
 

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