When a current I flows through two concentric conductor of radius a1,n a2 net magnetic field at their centre is
B = 
o/4
. 2 I (1/a1 + 1/a2)
when current flows in same direction n by the relation
B = o/4 . 2 I (1/a1 - 1/a2)
when current flows in opposite direction through the two circular conductors
Moderation Team
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