Question

The magnetic field due to a utility wire is 0.10 mT when you are at a distance of 10 meters from it. What current (in Amperes) flows through the wire?

Answer 1

Answer:

I = 5000 A

Explanation:

We will use Ampere's Law to calculate the current:

$B = \frac{\mu I}{2\pi r}$

where,

B = Magnetic Field Strength = 0.1 mT = 1 x 10⁻⁴ T

μ = Permeability of Free Space = 4π x 10⁻⁷ N/A²

I = Current = ?

r = radius = 10 m

Therefore,

$1\ x\ 10^{-4}\ T = \frac{(4\pi\ x\ 10^{-7}\ N/A^2)(I)}{2\pi(10\ m)}\\\\I = \frac{(1\ x\ 10^{-4}\ T)(2\pi (10\ m))}{4\pi\ x\ 10^{-7}\ N/A^2}$

I = 5000 A