|Try searching the web using the specific model number and a few appropriate words. |
Latitude xxxx "power jack"
Latitude xxxx "AC jack"
The specific model of a brand name system is shown on a label on the outside of the case somewhere, or it can often be determined by going to the brand name's web site.
For Dell computers, they have a Service Tag number - the specific model can be determined by using that on their site, or can often be determined there automatically by you downloading some software. The Service Tag number should be on a label on the outside of the case, probably on the bottom on a laptop, and is often also shown in the bios Setup.
The model is often also displayed on a Dell logo (graphical) screen early in the boot, but it's often not as specific as the specific model number.