Question

A long straight wire carries a current of 35 A. What is the magnitude of the field B at a point 20 cm from the w ire?

Answer 1

I = 35 A, r = 20 cm = 20 x 10^-2 m
B = \(\frac{\mu_{0} I}{2 \pi r}\)
= \(\frac{4 \pi \times 10^{-7} \times 35}{2 \pi \times 20 \times 10^{-2}}\)
= 3.5 x 10^-5 T