E.D.C Electronics-800mcq

What is the DC characteristic used to prove that the transistor is indeed biased in saturation mode?
a) I_C = βI_B
b) I_C > βI_B
c) I_C >> βI_B
d) I_C < βI_B

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Answer: d
Explanation: When in a transistor is driven into saturation, we use V_CE(SAT) as another linear parameter. In, addition when a transistor is biased in saturation mode, we have I_C < βI_B. This characteristic used to prove that the transistor is indeed biased in saturation mode.

Which of the following cases damage the transistor?
a) when V_CE is increased too far
b) when V_CE is decreased too far
c) when V_BE is increased too far
d) when V_BE is decreased too far

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Answer: a
Explanation: When V_CE is increased too far, collector base junction completely breaks down and due to this avalanche breakdown, collector current increases rapidly. This is not shown in the characteristic. In this case, the transistor is damaged.

The small amount of current which flows even when base current I_B=0 is called_________
a) I_BEO
b) I_CBO
c) I_CEO
d) I_C

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Answer: c
Explanation: In the cut off region, a small amount of collector current flows even when base current I_B is zero. This is called I_CEO. Since the main current is also zero, the transistor is said to be cut off.

Which of the following points locates the quiescent point?
a) (I_C, V_CB)
b) (I_E, V_CE)
c) (I_E, V_CB)
d) (I_C, V_CE)

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Answer: a
Explanation: The quiescent point is best located between the cut off and saturation point. I_E= V_EE/R_E, V_CB=V_CC-I_CR_L. It is denoted by ‘Q’

n I_CEO, wt does the subscript ‘CEO’ mean?
a) collector to base emitter open
b) emitter to base collector open
c) collector to emitter base open
d) emitter to collector base open

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Answer: c
Explanation: The subscript ‘CEO’ means that it is collector to emitter base open. It is called as the leakage current. It occurs in a reverse bias in PNP transistor. The total current can be calculated by I_C=βI_B+I_C.

The range of β is _________
a) 20 to 500
b) 50 to 300
c) 30 to 400
d) 10 to 20

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Answer: a
Explanation: Almost in all the transistors, the base current is less than 5% of the emitter current. Due to this fact, it is generally greater than 20. Usually it ranges from 20 to 500. Hence this configuration is frequently used when appreciable current gain as well as voltage gain is required.