Past exam question about electrostatic field and potential

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Homework Help Overview

The discussion revolves around a problem related to electrostatic fields and potentials, specifically using Stoke’s theorem and vector calculus identities to explore the relationship between the electric field E and the potential ψ. The original poster seeks clarification on whether a derivation is required to show that E = -∇ψ.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants question the meaning of the identity ∇x∇(Scalar)=0 and its implications for the problem. There is a discussion about whether a derivation is necessary and how to approach using Stoke’s theorem in this context.

Discussion Status

Some participants have provided insights into the identity and its relevance, noting that it relates to the curl of a gradient being zero. Others have suggested starting with the circulation integral and invoking Stokes' theorem to explore the implications for the electric field.

Contextual Notes

The original poster expresses uncertainty about the requirements of the question, particularly regarding the need for a derivation versus a conceptual understanding of the relationship between E and ψ.

ZedCar
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Homework Statement



Using Stoke’s theorem and the identities given, ∇x∇(Scalar)=0 deduce the relationship between electrostatic field E and potential ψ at a point in space, show that E = -∇ψ


Homework Equations





The Attempt at a Solution



Does this question mean show a derivation which uses Stoke’s theorem and mathematical identities to obtain E = -∇ψ ?

Or is something else required since it states, "∇x∇(Scalar)=0 deduce the relationship between electrostatic field E and potential ψ at a point in space". I wasn't sure if by a derivation arriving at E = -∇ψ then in effect this would be illustrated.

Thanks
 
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Can't read your question. What is ∇x∇(Scalar)=0 ?
 
rude man said:
Can't read your question. What is ∇x∇(Scalar)=0 ?

That's exactly the way its typed on the past exam paper ie ∇x∇(Scalar)=0
 
rude man said:
Can't read your question. What is ∇x∇(Scalar)=0 ?
Isn't that just the vector calculus identity that the curl of a gradient is zero?
 
Fightfish said:
Isn't that just the vector calculus identity that the curl of a gradient is zero?

Yes, this is an identity.
 
OK, I can't read the del sign in your posts. But OK, no problem now.

Start with the circulation integral: ∫E*ds = 0. This is a fundamental experimental observation. Then invoke Stokes' theorem to show that the curl of E must always be zero since the theorem applies to all possible closed paths.

Then invoke the fact that, in consequencxe of curl E = 0 there exists a potential function V such that E = - grad V.
 

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