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Define the term current density of a metallic conductor. Deduce the relation connecting current density (J) and the conductivity (sigma) of the conductor when an electric field E is applied to it. |
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Answer» Solution :According to Ohm.s law, we know that `V=RI = (rho l)/(A).I rArr V/l = rho . l/A` but `l/A = J` and `V/l = E` , hence we have `E= rho J ` or `J/E = 1/ rho= sigma ` ,where ` sigma `is the ELECTRICAL conductivity of given material. The relation`J/E = sigma " or" J = sigma E`is YET ANOTHER form of Ohm.s law. In VECTOR notations, ` VECJ = sigma vec E` |
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