Point charges, midpoint zero or non zero?

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Homework Help Overview

The discussion revolves around the electric field created by two point charges, +q and -q, positioned at +50 cm and -50 cm on the x-axis. The central question is whether the electric field at the origin, located between the two charges, is zero or nonzero, and if nonzero, in which direction it points.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the effects of the charges on a test charge placed at the origin, considering the forces exerted by each charge and whether they cancel each other out. There is uncertainty about the conditions under which the electric field would be zero or nonzero.

Discussion Status

Some participants suggest using the superposition principle to analyze the electric field, while others discuss the implications of the forces acting on a test charge. Multiple interpretations of the electric field's behavior at the midpoint are being explored, but no consensus has been reached.

Contextual Notes

Participants note that the nature of the charges (opposite polarity) influences the direction of the forces and the resultant electric field, and there is an acknowledgment of the need for further clarification on the setup and assumptions involved.

rcmango
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Homework Statement



Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Homework Equations





The Attempt at a Solution



Well I know the charges will be attracting each other because they are opposite in polarity. I'm not sure if the electric field will be zero or non zero. I do know that if the charges were the same polarity, then the midpoint in the middle would both be zero. Please help me figure this one out completely.
 
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rcmango said:
Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Use the superposition principle. Google "electric field" and "superposition".
 
Place a positive test charge at the origin. If the net Coulomb force on the test charge is zero, the electric field is zero; if the net Coulomb force is not zero, then the electric field is not zero and point in the same direction as the net Coulomb force.
 
rcmango said:

Homework Statement



Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?
Looking at the +q charge at +50 cm only, a negative charge would feel a force toward it, in the positive direction (and a positive charge in the negative direction). Looking at the -q charge at -50 cm only, a negative charge would feel a force away, in the positive direction (and a positive charge in the positive direction). The two forces add, they do not cancel.

Homework Equations





The Attempt at a Solution



Well I know the charges will be attracting each other because they are opposite in polarity. I'm not sure if the electric field will be zero or non zero. I do know that if the charges were the same polarity, then the midpoint in the middle would both be zero. Please help me figure this one out completely.
 

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