Electric fields and net charge

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Discussion Overview

The discussion revolves around the behavior of electric fields in relation to a sphere with a net charge of zero, particularly when influenced by an external charged object. Participants explore concepts of electric fields, induced charges, and the implications of static equilibrium on the experience of electric fields by charged objects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that a sphere with a net charge of zero does not experience an electric field, yet questions arise when a positively charged rod is brought near, causing electrons to move towards it.
  • Another participant asserts that the electric field inside a conducting sphere remains zero when placed in an external field due to induced surface charges, while the field outside the sphere is altered.
  • A participant reiterates the initial question about whether an object in static equilibrium, subjected to multiple electric fields that cancel out, can still be said to experience an electric field.
  • One participant explains that when a positively charged rod is near a conducting sphere, negative charges accumulate on the side facing the rod, creating an electric field vector directed towards the sphere on that side, while positive charges accumulate on the opposite side.
  • There is a clarification regarding the terminology of "experiencing an electric field," with a suggestion that it may refer to the forces acting on charges within the sphere.

Areas of Agreement / Disagreement

Participants express differing views on whether a sphere with a net charge of zero can be said to experience an electric field when influenced by an external charge. The discussion remains unresolved regarding the implications of static equilibrium on the experience of electric fields.

Contextual Notes

There are assumptions about the nature of the sphere (conducting vs. non-conducting) that may affect the discussion. The terminology used to describe the experience of electric fields and forces may also lead to different interpretations.

caljuice
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If a sphere has a net charge of zero, then it experiences no electric field right? But if you bring a + charged rod it, the electrons experience a field and all move towards it. But the net charge for the sphere is still zero since same number and electrons cancelling out. So do we say the electric field of the sphere is still zero when the electrons clearly experience a field?

Also if an charged object is in several electric fields, but the forces cancel out (static equilbrium), do we still say that object experiences an electric field?

Thanks.
 
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The E field inside the sphere is still zero when placed in an external field , The induced surface charges will make it cancel inside . But the polarized conducting sphere will alter the E field outside . On your second question We would say it doesn't experience an E field, It would be like being inside a hollow spherical conducting charged sphere .
 
caljuice said:
If a sphere has a net charge of zero, then it experiences no electric field right? But if you bring a + charged rod it, the electrons experience a field and all move towards it. But the net charge for the sphere is still zero since same number and electrons cancelling out. So do we say the electric field of the sphere is still zero when the electrons clearly experience a field?

Also if an charged object is in several electric fields, but the forces cancel out (static equilbrium), do we still say that object experiences an electric field?

Thanks.

Charge is relative, not absolute.
 
Assuming that it's a conducting sphere, when you bring the positively charged rod near the sphere, negative charges will accumulate on the surface of the sphere facing toward the rod, and positive charges will accumulate on the surface of the sphere facing away from the rod. Outside the sphere but near it, on the side facing the rod, an electric field vector E will point toward the sphere, and on the side facing away from the rod an electric field vector will point away from the sphere.

Your phrase about whether the sphere "experiences an electric field" is unusual and I don't know what it means. Do you mean "experience a force" as a result of being in the place where there is a field? The charges within in the sphere do experience such a force, and that is why they have moved to the locations on the surface where they have moved to.
 

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