The formula is given by Ampère's Law for a long straight conductor:
\[ B = \frac{\mu_0 I}{2 \pi r} \]
where \( B \) is the magnetic field induction, \( \mu_0 \) is the permeability of free space (\(4\pi \times 10^{-7} \, \text{T}\cdot\text{m/A}\)), \( I \) is the
Show more…