Vector Calculus: Is F=0 When ∇·F=0 & ∇×F=0?

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SUMMARY

In vector calculus, the conditions ∇·F=0 and ∇×F=0 do not imply that the vector field F is zero. A counterexample is provided with the vector field F = 3−x, which has a divergence of 3 and a curl of 0, demonstrating that F can be a non-zero constant vector field. This discussion clarifies that while both divergence and curl being zero are necessary conditions for certain types of vector fields, they do not guarantee that the vector field itself is zero.

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  • Proficiency in interpreting mathematical expressions involving unit vectors
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latentcorpse
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is it true that if \nabla \cdot \vec{F}=0 , \nabla \times \vec{F}=0 then \vec{F}=0?
 
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latentcorpse said:
is it true that if \nabla \cdot \vec{F}=0 , \nabla \times \vec{F}=0 then \vec{F}=0?

Suppose \vec F=3\hat x \ldots
 
the divergence of 3x is 3 not 0 though?
 
latentcorpse said:
the divergence of 3x is 3 not 0 though?

By \hat x, I mean what you might have seen as \hat \imath...
that is,
\vec F= (3) \hat \imath
or
\vec F= (3,0,0)
...that is, a nonzero constant vector field.
 

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