Electric Field and dipole moment

In summary, the conversation discusses a dipole moment that is symmetric along the y-axis and along the x-axis. The electric field at a distant point on the x-axis is given by E ~ (4*Ke*q*a)/(x^3). The speaker sets up an equation for E and ends up with a different answer from the one they are supposed to get. They realize their mistake and correct it.
  • #1
Gear300
1,213
9
There is a dipole moment that is symmetric along a y-axis and is along an x-axis. A charge -q is placed a distance a along the -x direction and a charge +q is placed a distance a along the +x direction, making the distance between the 2 charges 2a. I'm supposed to show that the electric field at a distant point on the +x axis is
E ~ (4*Ke*q*a)/(x^3).

I set the equation so that E = (-Ke*q)/(x+a) + (Ke*q)/(x-a) and ended up with
E = (2*Ke*q*a)/(x^2 - a^2), which for a distant point may round to (2*Ke*q*a)/(x^2). The answer they're looking for is different. What am I doing wrong?
 
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  • #2
E=Keq/r^2 not Keq/r.
 
  • #3
!...Such a simple mistake. Heh...oh well. Thanks, I got it.
 

FAQ: Electric Field and dipole moment

1. What is an electric field?

An electric field is a physical quantity that describes the influence that an electric charge has on other charges in its vicinity. It is a vector field, meaning it has both magnitude and direction, and is created by the presence of an electric charge.

2. How is an electric field measured?

The strength of an electric field is measured in units of newtons per coulomb (N/C). This is the amount of force, in newtons, that would be exerted on a positive test charge of 1 coulomb placed in the field. The direction of the field is given by the direction of the force on a positive test charge.

3. What is a dipole moment?

A dipole moment is a measure of the separation of positive and negative charges within a molecule or system of charges. It is a vector quantity, with magnitude equal to the product of the charge and the distance between the positive and negative charges, and direction from the negative to the positive charge.

4. How does a dipole moment affect an electric field?

A dipole moment can affect an electric field by creating a torque on the dipole in an external electric field. This torque causes the dipole to rotate, aligning itself with the external field. Additionally, a dipole moment can interact with other charges in the electric field, exerting a force on them and altering the overall electric field in its vicinity.

5. How are electric field and dipole moment related?

Electric field and dipole moment are related in that the electric field is directly proportional to the dipole moment. This means that as the strength of the electric field increases, the dipole moment also increases. In other words, the larger the dipole moment of a system, the stronger the electric field it creates.

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