The current density in a cylindrical wire of radius 4   mm is 4 × 10 6   A   m - 2 . The current through the outer portion of the wire between radial distances R 2 and R is _____ π   A .

Step-by-step solution

Current density is defined as current per unit cross-section area. Therefore, i = J A = J × π R 2 - R 2 4 ⇒ i = 4 × 10 6 × π × 16 × 10 - 6 × 3 4 ⇒ i = 48 π   A