In an n-p-n transistor amplifier, the collector current is 8 mA . If 80 % of the electrons from the emitter reach the collector, then ( and are current ratios)

Step-by-step solution

Given the collector current I_C = 8 mA and that 80 % of emitter electrons reach the collector, it follows I_C = 0.80 , I_E . I_E = 8 mA 0.80 = 10 mA The emitter current is the sum of the base and collector currents, I_E = I_B + I_C , leading to: I_B = 10 mA - 8 mA = 2 mA The common base current gain is = I_C I_E = 8 mA 10 mA = 0.8 . The common emitter current gain is = I_C I_B = 8 mA 2 mA = 4.0 or equivalently = 1- = 0.8 0.2 = 4.0 . This corresponds to option C .