# Two identical current-carrying coaxial loops,

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