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Define the term current density. |
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Answer» Solution :Current density at a point in a conductor is defined as the amount of current flowing per UNIT area of the conductor AROUNG that point proiveded the area `J = (I)/(A)` Current density is a vector quantity. Its direction is the direction of motion of positive CHARGE. The unit of current density is amper/`"meter"^(2), or [Am^(-2)]` Relation between J and E: `I = N A e v_(d)` ` = n Ae ((eE)/(m )tau )` `= n (A e ^(2) rau E)/(m)` `or I /A = ( n e ^(2) tau E)/( m )` or `J = (1)/(rho) E` `[ because J = I/A and rho = (m)/(n e ^(2) tau)]` `J = sigma E [ because sigma = (1)/(rho)]` |
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