In a lightning bolt, 13 C of charge flows in a time of 1.5*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 29 m from the bolt?

Answer 1

The current is
I = Q/(time) = 13/1.5*10^-3s = 8670 Amps

Use the formula for the B-field around an infinite linear current at distance R.

B = mu* I/(2 pi R)

Where mu is the permeabilty of free space.