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 ?

Explanation

`I = 90 A, r = 1.5 m`
`B= (mu_0I)/(2 pi r) = (4 pi xx 10^(-7) xx 90)/(2 pi xx 1.5) = 1.2 xx 10^(-5)` (south )