It's a desert topping and a floor wax Frank. . . .

I'll see you. . .

The O2 sensor is a voltage source ( chemical battery ). If exhaust oxygen is low / mixture too rich , there will be an imbalance on either side of the sensor that will generate an electrical current. If exhaust oxygen is high / mixture lean , the two sides balance each other out and there won't be any current generated.


And raise you. . .

Systems apply a bias voltage so the ECM knows the sensor is hot and it's output can be used for mixture adjustments. ( Closed loop )

"Using the data " and diagram on page 3 of the link below.

(AC Delco as in General Motors )
https://www.acdelcotechconnect.com/pdf/TechConnect+MayJune+2012+F.pdf