Arduino UNO Rev 3 polarity?

I would like to ask simple question about arduino uno power jack polarity.
which is positive, the needle (at the center of the power jack hole) or the outer circle?
Thank you.

center is +

creativen:
I would like to ask simple question about arduino uno power jack polarity.
which is positive, the needle (at the center of the power jack hole) or the outer circle?
Thank you.

Yes, positive. But if you were to wire a negative center pin voltage source via the connector there would be no damage as there is a on-board series polarity protection diode wired in to protect the board which will not function but will not be damaged by a negative center pin voltage source.

Lefty

Thank you all! I just want to make sure everything is working in safety.