# Mean Free Path of Magnetic Core

I don't understand how they got the mean free paths (ls) of each leg. I know that I should be calculating the longest + the shortest paths and divide them by two, but I don't know HOW I should be calculating these.

Thanks

• 'mean free path' is a phrase from a different branch of science. I think you mean 'effective length', though 'mean length' might be a simpler and adequate approximation. Sep 10 '19 at 9:58
• I meant to say, mean length path*
– user199242
Sep 10 '19 at 11:02
• or yes the effective length
– user199242
Sep 10 '19 at 11:03