Question

When transistors are used in digital circuits they usually operate in the

Answer 1

The answer is Saturation and Cut off region.

The transistor works as a closed switch in the saturation area and as an open switch in the cutoff zone. o/p can be a ‘0’ or a ‘1’ in digital circuits. So, in the saturation zone (closed switch), output ‘1’ is produced, whereas in the cut off zone (open switch), output ‘0’ is produced.
This is the zone where the transistor behaves like an open switch. The collector and base of the transistor are both opened as a result of the operation. In this mode of operation, the collector, emitter, and base currents are all zero.