Thank you for your question, it's a very good one.
wires are used to carry electricity. You could say that the electricity
flows inside a wire the same way that water flows in a tube. If you
have a big fat tube, you can send more water through it than you can
through a skinny tube. In the same way, a fat wire can carry more
electricity than a skinny wire.
OK, so what does this have
to do with putting a wire in liquid nitrogen? Well, it turns out that
liquid nitrogen is very very cold stuff (hundreds of degrees below
zero). It also turns out that when you make a wire cold, it makes it
easier for electricity to flow through the wire, (in the same way that
making a wire fat will make it easier for electricity to flow through
So, putting a wire in liquid nitrogen will make it very
cold, which will make it easier for it to carry electricity. (It will
also make it harder to bend, but that's another question).
(republished on 08/02/06)