What would happen if you use one leg of a 220 circuit and it's neutral to power a 110 light?

it will lite . <P>

<P></P>Well, you sorta answered your own question, if you are talking residential wiring. The transformer in front of the house supplies 220V, center tapped, to your house. (we are talking the USA, right?) Center tapped means that the secondary of the transformer feeding your house is supplying 220, but there is a wire in the center of the secondary coil that has 110 between it and either end of the coil. If you look in your fusebox (breaker box in any newer home) you will see breakers on the left and on the right. The ones on the left side supply power from one end of the coil into your house and the center tap, and the ones on the other side supply power from the other end of the secondary and the center tap. 220 volts goes from either end of the secondary and doesn't bother with the center tap. I think the answer to the question is, you'll make light. be careful fooling with the cords, though.