Battery light on Dashboard

Can anyone tell me what is causing the battery light on the dashboard to come on? Its flickering on and off when the car is traveling in excess of 65 mph or more. Thanks!

Your alternator is failing. Have a parts store or repair shop check it's output to confirm.

my battery light come on when i rev my engine to about 6000 rpm's

maybe the belt is just failing thats what it sounds like to me