magnetic field of a lightning bolt

[1timeuse]

In a lightning bolt, 14 C of charge flows in a time of 1.5 x 10^-3 s. Assuming that the lightning bolt can be represented as a long, straight line of current, what is the magnitude of the magnetic field at a distance of 27 m from the bolt?

do i use 27 m as the radius in the equation

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

[Tide]

In a lightning bolt, 14 C of charge flows in a time of 1.5 x 10^-3 s. Assuming that the lightning bolt can be represented as a long, straight line of current, what is the magnitude of the magnetic field at a distance of 27 m from the bolt?

do i use 27 m as the radius in the equation

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

Yes! That's just Ampere's law applied to a cylindrically symmetric current.