Whenever we observe the terminals of a BJT and see that the emitter-base junction is not at least 0.6-0.7 volts, the transistor is in the cutoff region. In cutoff, the transistor appears as an open circuit between the collector and emitter terminals. In the circuit above, this implies Vout is equal to 10 volts.

What happens when a transistor is cut-off?

If the transistor is cut-off, there is no base current, so there is no collector or emitter current. That is collector emitter pathway is open [See Below Fig.] (ii)]. In saturation, the collector and emitter are, in effect, shorted together.

When transistor is in cut-off the value of collector current is?

Cut-off Region

Here the operating conditions of the transistor are zero input base current ( I_B ), zero output collector current ( I_C ) and maximum collector voltage ( V_CE ) which results in a large depletion layer and no current flowing through the device. Therefore the transistor is switched “Fully-OFF”.