hi everyone...
it's 1st time 4 me 2 be here...but i have a question and hope that anyone has answer helps me...

in BJT when base current equals zero..there is collector current..of small value names collector saturation current..why this happens????

thnx in advance

 

Not "saturation" current, but "leakage" current. "Saturation" current is when the transistor is turned all the way on.

Leakage current happens because there is no such thing as a perfect transistor. The transistor has a very high resistance when turned off, but not an infinite resistance.