Electric field halfway between dipole isn't 0?

In summary, when considering a dipole with an electron and proton located at opposite ends, the net electric field at the middle point will be zero in magnitude but not in direction. This is because the electric fields from each particle cancel out in magnitude but add together in direction, resulting in a non-zero field at the middle point.
  • #1
MCATPhys
58
0
I was just wondering... say you have a dipole, and you wanted to find the net electric field right in the middle.

The electric field from the electron will be:
E = k(-1.60*10^-19)/r^2


The electric field from the proton will be the same magnitude, but opposite direction. Therefore, the net electric field should be zero right?
 
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  • #2
Say the dipole is located at the origin and oriented along they y axis. If the electron is at x=-a and the proton at x=a then they both contribute equally to the magnitude of E at the origin as you said, but think about the direction in which the E vector at the origin points due to each particle again. For a positive charge E points away and for a negative charge E points towards right?
 
  • #3
ohhh - so since they are both in the same direction... they add to a non-zero number...?
 
  • #4
Correct. They both point in the same direction, that is, in the direction from the proton to electron. So the field there is nonzero.
 
  • #5
It's very large in between the charges.
If the charges were the same polarity there would be zero field at a point but this isn't a dipole.
 

1. Why isn't the electric field zero at the midpoint between two equal and opposite charges?

The electric field at any point in space is determined by the magnitude and direction of the charges present in that region. In the case of a dipole, the two charges have equal but opposite magnitudes, causing the electric fields to cancel out in some regions and add up in others. At the midpoint between the two charges, the electric fields do not completely cancel out, resulting in a non-zero electric field.

2. Is the electric field at the midpoint always non-zero in a dipole?

No, the electric field at the midpoint between two charges will only be non-zero if the two charges have equal but opposite magnitudes. If the charges are not equal, the electric field at the midpoint may be zero or non-zero depending on the specific arrangement of the charges.

3. How does the distance between the charges affect the electric field at the midpoint?

The distance between the charges in a dipole does not directly affect the electric field at the midpoint. However, as the distance between the charges increases, the strength of the electric field decreases due to the inverse square law. This may result in a smaller non-zero electric field at the midpoint.

4. Can the electric field at the midpoint be zero in a non-symmetric dipole?

Yes, the electric field at the midpoint of a non-symmetric dipole can be zero. This can occur if the two charges are not directly opposite each other or if the magnitudes of the charges are not equal. In this case, the electric fields from the two charges will not completely cancel out at the midpoint.

5. How does the orientation of the dipole affect the electric field at the midpoint?

The orientation of the dipole does not affect the magnitude of the electric field at the midpoint, but it does affect the direction. If the dipole is oriented perpendicular to the line connecting the two charges, the electric field at the midpoint will be parallel to the line. If the dipole is oriented parallel to the line, the electric field at the midpoint will be perpendicular to the line.

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