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Electric Field due to a Dipole (not on a zaxis) 
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#1
Sep609, 11:08 PM

P: 115

1. The problem statement, all variables and given/known data
The figure shows an electric dipole. What is the magnitude of the dipole's electric field at point P, located at distance r >> d? 2. Relevant equations 3. The attempt at a solution I suppose I could define the angle with which I could write Ey = Esin[tex]\theta[/tex], but this problem is a webassign.com problem, so it's online and I can't define anything. The magnitude of the electric field at p due to the dipole would be very small, and I first estimated it to be zero (since the problem asks for an estimation anyway). Without defining and using a theta, how could I represent the magnitude of the electric field? 


#2
Sep709, 02:27 AM

P: 39

Just introduce theta temporarily. It goes away in the end since you know what it is.
The electric field vectors of the two charges add in the [itex]y[/itex] direction and cancel in the [itex]x[/itex] direction. Hence [tex] \vec E = E_y = (2 q/R) \sin(\theta) [/tex] where I will let you write down [itex]R[/itex] and [itex]\sin(\theta)[/itex] in terms of [itex]r[/itex] and [itex]d[/itex]. The rest you can do. 


#3
Sep709, 09:02 AM

HW Helper
P: 4,439

The electric field E = 1/4πε_{ο}*q/[r^{2} + (d/2)^{2}] Their ycomponents cancel out and xcomponents add. 


#4
Sep709, 02:17 PM

P: 39

Electric Field due to a Dipole (not on a zaxis)
I maintain that the y components add. Think of the magnetic field lines of the Earth at the equator.



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