A metallic conductor of circular cross-section has

Solution

The current density J is given as a function of the radial distance r from the center of the circular cross-section: J = Jₒ(1−r/R) where Jₒ is a constant and R is the radius of the conductor.   To find the total current I through the conductor, we need to integrate the current density over the cross-sectional area of the conductor. Consider a small circular area element dA at a radial distance r from the center. The area of this element is dA = 2πrdr. The current dI through this area element is given by dI = JdA. dI = Jₒ(1−r/R) (2πrdr) To find the total current I, we integrate dI over the entire cross-section of the conductor, from r = 0 to r = R: