If I wanted to know how to find the magnetic flux through a loop, I'd need to know the current flowing near it. If that current is in the form of a spark, how do I represent that? The spark is nearly instantaneous, and I've got no idea how to determine the number of charges which flowed within it... essentially - I want to find the magnetic flux in a loop due to a spark nearby. I know that the breakdown of air is at .97MV/m... and suppose I know the length of the spark. where do I go from there? do i need more information? any thoughts? thanks!