Question:
Two identical current-carrying coaxial loops, carry current I in an opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C,
(a)
$\oint_{c} B . d l=\mp 2 \mu_{0} I$
(b) the value of
$\oint_{c} B \cdot d l$ is independent of sense of $c$
(c) there may be a point on C where B and dl are perpendicular
(d) B vanishes everywhere on C
Solution:
(b) the value of
$\oint_{c} B \cdot d l$ is independent of sense of $C$
(c) there may be a point on C where B and dl are perpendicular