The Current Density of 1 $\times$ 10⁵ A/m² Is Uniform Across a Wire Whose Radius Is

Multiple Choice

The current density of 1.5 $\times$
10⁵ A/m² is uniform across a wire whose radius is 4.0 mm. The current through the outer portion of the wire between the radii of 3.0 mm and 4.0 mm is

A) 1.1 A.
B) 2.2 A.
C) 3.3 A.
D) 4.4 A.