Question

A long, straight, hollow conductor (tube) carrying a current has two sections E and C of unequal cross-sections joined by a conical section B. 1, 2 and 3 are points on a line parallel to the axis of the conductor. The magnetic fields at 1, 2 and 3 have magnitudes $B_1,B_2$ and $B_3$ :

• A. $B_1=B_2=B_3$
• B. $B_1=B_2\ne B_3$
• C. $B_1<B_2<B_3$
• D. $B_2$ cannot be found unless the dimensions of the section B are known

Answer 1

Answer: (A)

$B_1=B_2=B_3$

To find the magnetic field outside a thick conductor , the current may be assumed to flow along the axis .as points 1, 2 and 3 are equidistant from the axis . $B_1=B_2=B_3$