Question

A magnetic field of 9.6 x 10–3 T is measured 1.6 x 10–3 m away from a current carrying wire. What is the electric current in A?

The permeability of free space is μ0 = 4π x 10–7 T m /A.

Answer 1

The magnetic field of a current carrying wire at a distance r from it is,
B = (_o * I) / (2 * r)
Where _o is the vacuum permeability and I is the current.
I = (B * 2 * r) / _o

Given that B = 9.6 * 10^-3 T
r = 1.6 * 10^-3 m
Substituting values,
I = [(9.6 * 10^-3) * 2 * (1.6 * 10^-3)] / (4 * 10^-7)
= 76.8 A