Originally Posted by daddle
The electric field and the magnetic field are effects of the same thing. They are inseparable. So as the Faraday cage acts on a electric field it acts on the magnetic field too.
The magnetic shielding materials such as iron or Mu Metal are used for static magnetic fields such as the earth's or a nearby engine
. These static magnetic fields produce no current so the Faraday cage is ineffective. But as they induce no electric current they cannot cause electrical damage except in special cases.
Here's the way I think about it. Electromagnetic wave are alternating, interlocking loops of electrical and magnetic energy, just like a chain. Straight out of book 2, Halliday and Resnick if I recall
my 1st year physics.
If the boat touches the chain, lets ignore diffraction effects, it will touch one or the other type of link more. Any touching by a conductive container of an electrical link will affect the mag link connected to that e-link. Since the boats are all approximately the same size, for this kind of physics question, then it stands to reason that longer wavelengths (lower freq) are more likely to have a lot less of of an e-link touching the container meaning that the more of the energy is magnetic.
Any conductive material will induct an electric current from a changing magnetic field. But it seems to me that not all of the magnetic energy would be inducted some would penetrate the conductive shell and induct currents in anything conductive within the shell unless the shell was ferro-manetic.
The question becomes at what frequency does an em wave start acting like it is static for these purposes and the material of the faraday cage start becoming important. I don't really know the answer for lightning.
I know that for sensitive experiments the cage material starts to become important at about 100kHz and below. It seems reasonable that lightning would be somewhere below that. The peak energy for lightning is at about 5-10kHz. I suspect that cage material has at least some effect on level of protection, just don't know for sure how much and can't find confirming or contradictory info.
In sum, cage material being steel
may help and can't hurt.