How to connect to TV with USB to AV cable? I tried to connect, but nothing happened! (10.04 Lucid)
I think you might be talking about a cable to be used with a digital camera, not a computer.
does yours look like this?
This cable is meant to connect a digital camera to a TV. It's useless with computers
There are adaptors, such as the one in the first image, that do this job. A few of them work well with Ubuntu, you should carefully select one that does if you're going to buy one, because may of them have problems.
But, I think you're probably not talking about this thing. So, no, a simple cable will not work.