Q. The earth’s magnetic induction at a certain point is $7 \times 10^{- 5}\ Wbm^{- 2}$. This is to be annulled by the magnetic induction at the center of a circular conducting loop of radius 15 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) From $\ \ \ B = \frac{\mu_{0}i}{2r}$
$7 \times 10^{- 5} = \frac{4\pi \times 10^{- 7} \times i}{2 \times 5 \times 10^{- 2}}$
$\ i = \frac{7 \times 10^{- 5}}{4\pi \times 10^{- 6}} = 5.6$ A
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.