Question

An infinitely long hollow conducting cylinder with inner radius `(R )/(2)` and outer radius `R` carries a uniform current ra density along its length . The magnitude of the magnetic field , ` | vec(B)|` as a function of the radial distance `r` from the axis is best represented by
A.
B.
C.
D.

Answer 1

Correct Answer - D
For ` r gt ( R )/(2) , B = 0 `
For `( R )/(2) le rlt R ,
` B = ( mu_(0))/(2) [ r - ( R ^( 2)) /( 2 r )] J`
For ` rgt R ` , ` B = (mu_(0)i)/(2 pi r)`