Background apps and the battery Every time I use Google Search, the browser or the music player of my Samsing Galaxy S II (Android 2.3), even if I push the back button until it brings me back to the home screen, the apps keep running in background (seen in the "Active Applications" widget).

Do they consume my batery? Do they enter in some kind of supended mode, so they don't consume the CPU? If they do consume, is there any configuration to make them really close when I push the back button?
I've asked a similar question about my browser.  The consensus seems to be that these apps are normally pretty dormant when in the background, and my browser was behaving strangely.  Android's designed so that you don't need to exit apps (the system manages suspending and killing them); so, unless you notice an app consuming an abnormal amount of CPU time while in the background, it should be safe to leave them be.