A lightning bolt may carry a current of 1.50 × 10⁴ A for a short period of time. Supposing that the bolt extends far above and below the point of observation, what is the resulting magnetic field 100 m from the bolt?

Question

Quizplus · Accepted Answer

The magnetic field $B$ at a distance $r$ from a long, straight conductor carrying current $I$ is given by Ampère's law: $B = \frac{\mu_0 I}{2\pi r}$, where $\mu_0 = 4\pi \times 10^{-7} \, \text{Tm/A}$. Substituting $I = 1.50 \times 10^{14} \, \text{A}$ and $r = 100 \, \text{m}$, we find $B = \frac{(4\pi \times 10^{-7} \, \text{Tm/A}) \times (1.50 \times 10^{14} \, \text{A})}{2\pi \times 100 \, \text{m}} = 30 \, \mu\text{T}$.

A Lightning Bolt May Carry a Current of 1