Shakran,
I have forgotten more about electricity than you will ever know. So don't fucking call me stupid.
Old dimmer switches that use a "variable resistor" (aka rheostat) haven't been on the market for as long as I can remember. You must be pretty old.
I was correct in what I wrote, here's a quick link for you to do a little homework and learn before you go spouting off calling people stupid.
http://www.factsfacts.com/MyHomeRepair/DimmerSwitch.htm
You will note from the sinusoidal wave that the dimmer works by shutting the power off during a certain period of the sine wave. During the period of the wave in which the power is "on" one can still get a 120 Volt shock.
Want more proof, take a volt meter with a very high impedence to circuit with a dimmer switch. The volt meter will read 120 volts regardless of where your dimmer is set.
The voltage is constant.
Here's an even better link, read it too and learn.
http://home.howstuffworks.com/dimmer-switch.htm