The current density varies with radial distance r as `J=ar^(2)` in a cylindrical wire of radius R. The current passing through the wire between raidal distance `R//3` and `R//2` is

Options

A. `(65piaR^(4))/(2592)`
B. `(25piaR^(4))/(72)`
C. `(65pia^(2)R^(3))/(2938)`
D. `(81pia^(2)R^(4))/(144)`

Answer

A