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SATURATION AND CUT-OFF

CUT OFF
Cut off occurs when there is no forward bias on the transistor.
There is no base or collector current.
Since there is no current through the collector load resistor, then there is no voltage across the load resistor.
Therefore the collector voltage is the same as the supply voltage.

SATURATION
This occurs when there is so much forward bias that a very high collector current is produced.
The resulting voltage drop across the load resistor is almost equal to the supply voltage.
This means that the collector voltage is almost zero.