The Dancing Pixies explanation of Quantum Electrodynamics
Once, years ago, when I was fitting a hub generator lighting system to his bike, a hippie asked me "Why do there have to be two wires to the lamp?"
Amazingly I stayed calm and explained it in the following way:
In the hub there is a well where bits of light are found. When the wheel goes round, these are brought to the surface and Pixies collect them in buckets and dance up the wire to the lamp and throw the light out of the front of the lamp. The Pixies love to dance and rush into the wire, filling it completely. If there was only one wire they wouldn't be able to get back to the well to get more light to fill up their buckets, so two wires are needed, one for each direction.
I didn't continue this analogy to explain that as bike 'dynamos' are actually alternators the Pixies would be changing directions constantly.
Amazingly I stayed calm and explained it in the following way:
In the hub there is a well where bits of light are found. When the wheel goes round, these are brought to the surface and Pixies collect them in buckets and dance up the wire to the lamp and throw the light out of the front of the lamp. The Pixies love to dance and rush into the wire, filling it completely. If there was only one wire they wouldn't be able to get back to the well to get more light to fill up their buckets, so two wires are needed, one for each direction.
I didn't continue this analogy to explain that as bike 'dynamos' are actually alternators the Pixies would be changing directions constantly.