(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A rod of dielectric material is spun about it's axis with angular velocity [tex]\omega[/tex]. A uniform magnetic fieldBexists in a direction along the axis of the bar. Determine a charge distribution which produces the same electric field as does the rotating rod. The electric susceptibility of the material isx_{E}

2. Relevant equations

3. The attempt at a solution

The force on a charge q at a distance r is F=q*[tex]\omega[/tex]*r*B and the electric field is E=r*B*[tex]\omega[/tex].

The polarization of the rod at distance r is P=x_{E}*[tex]\epsilon[/tex]_{0}*[tex]\omega[/tex]*B*r.

So the volume distribution of charge should be -div P = -([tex]\partial[/tex]P_{r}) / ([tex]\partial[/tex]*r). But according to the book it should be

-div P = -([tex]\partial[/tex]P_{r}) / ([tex]\partial[/tex]*r) - (P_{r}) / r .

Could somebody please explain why it should be that way?? thx

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# Homework Help: Volume distribution of charge

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