Question

A current I flows around a closed path in the horizontal plane of circle as shown in the figure The path consists of eight arcs with alternating radii r and `2r` . Each segment of arc subtends equal angle at the common centre `P` The magnetic field produced by current path at point `P` is
.
A. `(3)/(8)(mu_(0)I)/( r )` , perpendicular to the plane of the paper and directed inward .
B. `(3)/(8)(mu_(0)I)/( r )` , perpendicular to the plane of the paper and directed outward .
C. `(3)/(8)(mu_(0)I)/( r )` , perpendicular to the plane of the paper and directed inward .
D. `(3)/(8)(mu_(0)I)/( r )` , perpendicular to the plane of the paper and directed outward .

Answer 1

Correct Answer - A
`B =(mu_(0))/(4pi) (I)/(2r) xx pi + (mu_(0))/(4pi) (I)/(r) xx pi`
`=(mu_(0)I)/(4r)[(1)/(2) +1]=(3)/(8) (mu_(0I))/(r)o.` .