Question

Two long current carrying conductors are placed parallel to each other at a distance of $8\, cm$ between them. The magnitude of magnetic field produced at mid-point between the two conductors due to current flowing in them is $300\, \mu T$. The equal current flowing in the two conductors is :

• A. 30 A in the same direction.
• B. 30 A in the opposite direction.
• C. 60 A in the opposite direction.
• D. 300 A in the opposite direction.

Answer 1

Answer: (B)

$B$ at $O =2 \frac{\mu_{0} I }{2 \pi r }$
$\frac{2 \times 4 \pi \times 10^{-7} I }{2 \pi 4 \times 10^{-2}}=3 \times 10^{-4} T$
$I =30\, A$ in opp. direction