How many sensors can my Uno power?

I am embarrassed to ask such a noob question.

I am getting started with an Uno R3 and a box of sensors from eBay. I managed to make a bluetooth transceiver work with an LED. Yay.

Now I want to add another sensor into the mix. I believe the other sensor takes 5V. How do I know how much power I have available by this (USB-powered) Uno?

I don't have documentation on most of my sensors, should the power consumption normally be printed on the sensor/dongle? Does the fact that the Uno can be powered by a 9V battery mean that its max power output is 9V?

You need to know the power requirements for each sensor. The current draw can in many cases be measured using a DVM. Buy one if you don't already have one.

Does the fact that the Uno can be powered by a 9V battery mean that its max power output is 9V?

Power is current times voltage.

9V batteries are nearly useless for anything but a smoke detector, and very short, low power Arduino experiments (as you will learn).

Thank you very much for the information. So it can be powered by more than just the 9V? How much can you give it?

hackr: How much can you give it?

All explained here. As you'll see, 7-12V recommended, but the higher you go from 7V, the more work the regulator has to do.

The standard Arduino can be powered via the barrel jack from a source delivering anywhere from 7 to 12 volts. The closer to 7 volts, the better.