Hi I am doing a project with arduino uno using 12v battery supply. Is there any way to power arduino uno using 12v?how to connect to arduino uno?
Yes. Connect the +terminal to Vin and the -terminal to ground. Or, get a connector and power it through the barrel jack.
You plug the 12V into the barrel jack of the Arduino. This sends the voltage to a regulator that drops it down to 5V.
Be aware that there is limited current available for powering other things from the Arduino's 5V pin or from the pins themselves. You should be good for about 200mA of current but any more and you risk the regulator over heating. If you need more then use a step down switching regulator sometimes called a buck regulator to get the voltage down to 5V efficiently. There are lots of these around if you search for them.
I think you should read the above replies backwards. Uno regulators are pretty crude and get quite hot enough using 9v, so 12v would just make it worse. I submit the inconvenience of a decent 5v switching regulator would be made up for by your piece of mind -more so if you add more peripherals.