250+ TOP MCQs on The Common Collector Configuration and Answers

Electronic Devices and Circuits Multiple Choice Questions on “The Common Collector Configuration”.

1. The current amplification factor ϒdc is given by_________
A. I_E/I_B
B. I_B/I_E
C. I_C/I_E
D. I_E/I_C
Answer: A
Clarification: When no signal is applied, then the ratio of emitter current to base current is called as ϒ_dc of the transistor. As the collector is common to both input and output circuits, hence the name common collector configuration.

2. The relation between α and β is given by _________
A. 1/(1-α)=1- β
B. 1/(1+α)=1+ β
C. 1/(1-α)=1+ β
D. 1/(1+α)=1- β
Answer: C
Clarification: The current amplification factor (β) is given by I_C//I_B. When no signal is applied, then the ratio of collector current to the base current is called current amplification factor of a transistor. β is an ac base amplification factor. α is called as current amplification factor. The relation of I_C and I_B change as I_C= βI_B+ (1+ β) I_CBO.

3. The CC configuration has an input resistance_________
A. 500kΩ
B. 750kΩ
C. 600kΩ
D. 400kΩ
Answer: B
Clarification: It has a high input resistance and very low output resistance so the voltage gain is always less one. It is used for driving a low impedance load from a high impedance source.

4. The application of a CC configured transistor is_________
A. voltage multiplier
B. level shifter
C. rectification
D. impedance matching
Answer: D
Clarification: The most important use of CC transistor is an impedance matching device. It is seldom used for amplification purposes. The current gain is same as that of CE configured transistor.

5. What is the output resistance of CC transistor?
A. 25 Ω
B. 50 Ω
C. 100 Ω
D. 150 Ω
Answer: A
Clarification: The CC transistor has a very low value of output resistance of 25 Ω. The voltage gain is always less one. It is used for driving a low impedance load from a high impedance source.

6. Increase in collector emitter voltage from 5V to 8V causes increase in collector current from 5mA to 5.3mA. Determine the dynamic output resistance.
A. 20kΩ
B. 10kΩ
C. 50kΩ
D. 60kΩ
Answer: B
Clarification: r_o=∆V_CE/∆I_C
=3/0.3m=10kΩ.

7. A change in 300mV in base emitter voltage causes a change of 100µA in the base current. Determine the dynamic input resistance.
A. 20kΩ
B. 10kΩ
C. 30kΩ
D. 60kΩ
Answer: C
Clarification: r_o=∆V_BE/∆I_B
=300m/100µ=30kΩ.

8. The point on the DC load line which is represented by ‘Q’ is called _________
A. cut off point
B. cut in point
C. breakdown point
D. operating point
Answer: D
Clarification: The point which represents the values of I_C and V_CE that exist in a transistor circuit when no signal is applied is called as operating point. This is also called as working point or quiescent point.

9. When is the transistor said to be saturated?
A. when V_CE is very low
B. when V_CE is very high
C. when V_BE is very low
D. when V_BE is very high
Answer: A
Clarification: When V_CE is very low, the transistor said to be saturated and it operates in saturated region of characteristic. The change in base current I_B does not produce a corresponding change in the collector voltage I_C.

10. The input resistance is given by _________
A. ∆V_CE/∆I_B
B. ∆V_BE/∆I_B
C. ∆V_BE/∆I_C
D. ∆V_BE/∆I_E
Answer: B
Clarification: The ratio of change in base emitter voltage (∆V_BE) to resulting change in base current (∆I_B) at constant collector emitter voltage (V_CE) is defined as input resistance. This is denoted by r_i.