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

I = 90 A, r = 1.5 m
B = \(\frac{\mu_{0} I}{2 \pi r}\)
= \(\frac{4 \pi \times 10^{-7} \times 90}{2 \pi \times 1.5}\)
= 1.2 x 10^-5 T (South)