Q. A horizontal overhead powerline is at a height of 4 m from the ground and carries a current of 100 A from east to west. The magnetic field directly below it on the ground is $\left( \mu_{0} = 4\pi \times 10^{- 7}\ {TmA}^{- 1} \right)$
A) $2.5 \times 10^{- 7}\ T,\ southward$
B) $5.0 \times 10^{- 6}\ T,\ northward$
C) $5.0 \times 10^{- 6}\ T,\ southward$
D) $2.5 \times 10^{- 7}\ T,\ northward$
Explanation
(c) $B = \frac{\mu_{0}I}{2\pi R}$
Direction is given by Right hand palm value No. 1
$B = \frac{2 \times 10^{- 7} \times 100}{4}\ T$ towards south
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.