Battery/Alt./Serpentine belt...

What is your question?

The other day on my way home my car lost power lights ect. Went to have batt. tested, said was bed, purchased new one, proceded to test whether it was getting a charge...was not, I then noticed some remnants of belt being chewed up. So my thought was the belt broke, however the power steering still works....so, its the belt, or alternator?? Any thoghts?? The car only has 61k mi. Thank you.