So what happens when you REDUCE the resistance. In other words, what makes a speaker rated at 8 ohms different than a speaker rated at 4 ohms. Well, as you might have guessed, it is easier for electrons to flow through the speaker's motor. In fact, it is now half as easy.
ALL OTHER THINGS BEING EQUAL, what this means is that now your 4 ohm speaker is now TWICE AS LOUD as your 8 ohm speaker. Current can now flow twice as easier so if we had a "perfect" amplifier, it would now produce EXACTLY twice as many watts as before.
MANY AMPLIFIERS in fact DO produce nearly twice as many watts when the resistance (or Ohms) is cut in half. But........ Amplifiers cannot produce infinate current as heat becomes an enemy that will destroy an amplifier. That's why the "better" amplifiers can INDEED handle speakers with impedences of 4 or even 2 ohms! Every time, this increases the maximum watts (or current) that amplifier can produce. On the other hand, lower price amplifiers (like low end Sony, Kenwood, Pioneer, and Technics amplifiers) are only 8 or perhaps 6 ohms "stable". This means that if you try to connect a speaker with a low resistance, like say around 4 ohms, you will be running too much current through your speaker connections and cause your amplifier to overheat. This is also why you cannot double up speakers for each speaker connection. By connecting two speakers to ONE speaker connection, you have now made it TWICE as easy for electrons to flow from positive to negative (or vice versa), in a sense, by doing this you have split the resistance (or ohms) by two.
Anyway, going back to the original question, the question seemed to suggest that house current has an "Ohm" rating. 110 represents the voltage. House current is usually connected to a circuit breaker that allows no more than 30 ampers of current to a source. "Ohms Law" states that volts x amperage = watts. In other words, if you hook up your 110 volt source to a 100 watt light bulb, by doing some simple algegra, we see that 100 watts =110 volts X .9 ampers.
This is a little differenent question, but a good way to think of watts is the TOTAL amount of electricity used. I have always liked the water in a hose analogy to explain electricity. volts is the SPEED of that water and amperage is how wide the hose is. A car uses 12 volts, a very SLOW moving electricity flow but much larger amperages (larger pipes, and IN FACT YOU WILL find in a car the cables are indeed LARGER than wires used in the home). Because the flow in a car is moving "slower", it is much, much safer (this is why you can touch both the positive and negative posts of a battery and not fry yourself. Although from a physics perspective, the electrons are not technically moving "slower", this is a good way to keep things striaght.
I hope this helps.
Nick