Q. The earth’s magnetic induction at certain point is $7 \times 10^{- 5}\ Wb/m^{2}$. This is to be annulled by the magnetic induction at the centre of a circular conducting loop of radius $5\ cm$. The required current in the loop is
A) 0.56 $A$
B) 5.6 $A$
C) 0.28 $A$
D) 2.8 $A$
Explanation
(b) $\frac{\mu_{0}}{4\pi} \times \frac{2\pi i}{r} = H \Rightarrow \frac{(10^{- 7}) \times 2 \times 3.142 \times i}{0.05} = 7 \times 10^{- 5}$
$\therefore i = \frac{7 \times 0.05 \times 10^{- 5}}{2 \times 3.142 \times 10^{- 7}} = \frac{35}{2 \times 3.142} = 5.6\ amp$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.