Galaxy Tab is not being charged through USB Cable Currently i am using Samsung Galaxy Tab, model is GT-P1000, to test my application, so i usually attach it with PC through USB cable and it is attached for a whole day though it is showing low battery at the end of day. but it should charge the battery same as the other phone when we attach it with USB.

Does anybody know, what may be the problem why my samsung galaxy tab is not being charged through USB cable?
Tablets have larger batteries than phones and may be unable to sufficiently charge from the half amp limit of a USB port, especially while they are fully on (screen on and full speed processor clock).  

Some will barely charge if the screen is off but come with high current 5v "usb-like" wall chargers, others use a higher voltage charger on a custom connector - typically something round.  Sometimes the "usb-like" ones are actually special cables with extra pins that tell the tablet that a special high-current charger is being used.

Check your user manual, or try the supplied charger.