Question

A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?

Answer 1

Magnetic field, $B=\frac{{\mu }_{o}I}{2\pi r}$

$B=1.2\times {10}^{-5}T$

Current flows from east to west, point is below the powerline.

Using right hand thumb rule, direction of B is southward.