Does a wormhole on the event horizon keep working? Recently the discovery of how to build a magnetic wormhole has been all over the news. These wormholes tunnel magnetic fields instantly from one point to another point. (Although the current model is on the nanometer scale)
My question is, if one of these wormhole machines was dropped into a black hole would it keep working when it is half way across the event horizon?
 A: An event horizon is not a magic place where magic things happen.
For instance in universes without dark energy and that are denser than ours (denser than the critical density actually) there are no event horizons. Even for extremely massive stars because everything eventually gets crushed in a big crunch.
An event horizon is an imaginary surface between a region where you can escape to get infinitely far away (versus a region where you cannot). You actually have to bring in the idea of an infinitely far away. Something we've never seen, never will see, and might not even exist.
So if you can use wormholes to escape away from a really dense star then there never was an event horizon since the was no region where you couldn't escape.
So with wormholes there are no event horizons since you can always escape. If the universe is finite in size there are no event horizons since there is nowhere to escape to. And if there is a big crunch there is no escape because everything getting crushed. In all these examples there aren't two regions hence no imaginary surface between them.
Classical gravity like General Relativity doesn't have some magic strength or effects at an event horizon. It's like a credit card. There is a magic payment amount equal to the interest. Pay less than that and you will never escape the debt, pay more and you can pay it off. But there isn't a magically amount of debt, just a cut off payment amount between the region of payment amounts where you escape the debt and where you don't.
As for the magnetic wormhole you mention, it isn't a wormhole it is a tube wrapped in a cylindrical superconductor to shield it and then with a magnetic cloak around it so (macroscopic) magnetic fields can propagate around it as if the superconducting cylinder and the tube inside it wasn't there.
And the word macroscopic is important. The idea is that you have lots of atoms arranged in funny shapes so that when you average the magnetic field over a region centered at a point and use the average value in that region as if it were the value at that point then it looks looks like it behaves in a funny way.
Averages can be weird. A person can move to a new town and because of the move the average income of both towns can increase (just make him poorer than average in the first town and richer than average in the new town)
The actual microscopic magnetic fields aren't doing anything different. And most importantly the two ends of the cylinder are just as far apart you are simply sending magnetic fields through a tube region where other magnetic fields are excluded and where if you try to send magnetic fields in that region from the wrong direction then their averages get diverted around the tube in a net way that is as if there was no tube there and the averages changes as if they traveled through empty space. Except they didn't. 
If you stuck one end across the event horizon then the microscopic fields follow the normal rules and nothing will escape the black hole. Your device will either have to all go through or else you'll have to rip it apart because no backsies on the part you put inside.
