In an NPN transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector, the emitter current (iE) and base current (iB) are given by 
(a) iE = –1 mA, iB = 9 mA
(b) iE = 9 mA, iB = – 1 mA
(c) iE = 1 mA, iB = 11 mA
(d) iE = 11 mA, iB = 1 mA

(d) 

ic=90100×iE10=0.9×iE=11mAAlso iE=iB+iciB=11-10=1mA

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