4 ms·There are better materials to make a Faraday cage out of, but foil is cheap, I'll concede that.by FFP999 3y agoThere are better materials to make a Faraday cage out of, but foil is cheap, I'll concede that.swader999 3y agoIt's pretty hard with tinfoil. Try it with an am radio. It takes several layers, no small gaps to kill the signal.FFP999 3y agoTIL.