Which officer rank is identified by one sleeve stripe that is 0.5"?

The officer rank identified by one sleeve stripe that is 0.5 inches is indeed Ensign. In the U.S. Navy and Coast Guard, the rank of Ensign is the lowest commissioned officer rank. It represents the beginning of an officer's career and is denoted by a single gold bar insignia, which corresponds to the one sleeve stripe measuring 0.5 inches.

This stripe is a part of the uniform that serves to indicate rank visually and is critical for recognition in both formal and informal settings. Understanding this basic structure of rank insignia is essential in the military because it helps establish hierarchies and authority on board ships and in various operational settings.