Concepts Of Physics MCQ Edition [Volume 2]PhysicsSemiconductors and Semiconductor Devices
Suppose i_E , i_C , and i_B denote the emitter current, the collector current, and the base current, respectively, for a given transistor. Which of the following statements hold true?
Options
- Ai_B is much smaller than i_E
- Bi_C is slightly greater than i_E
- Ci_C is slightly smaller than i_E
- Di_B is much greater than i_E
Correct answer
C. i_C is slightly smaller than i_E
Step-by-step solution
In a transistor, the emitter current i_E is the sum of the base current i_B and the collector current i_C . i_E = i_B + i_C The base region is very thin and lightly doped, so only a very small fraction of the charge carriers from the emitter recombine in the base. Thus, the base current i_B is very small, typically about 1 % to 5 % of the emitter current i_E . Therefore, i_B is much smaller than i_E . Since i_C = i_E - i_B and i_B is a small positive value, the collector current i_C is slightly smaller than the emi