Tuesday, 1 November 2016

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ELECTRICAL ENGINEERING IMPORTANT MCQ-TRANSISTOR BIASING



1. Transistor biasing represents ……………. conditions
  1. a.c.
  2. d.c.
  3. both a.c. and d.c.
  4. none of the above
Ans : 2
2. Transistor biasing is done to keep ………… in the circuit
1.Proper direct current
2.Proper alternating current
3.The base current small
4.Collector current small
Ans : 1

3. Operating point represents …………..
1.Values of IC and VCE when signal is applied
2.The magnitude of signal
3.Zero signal values of IC and VCE
4.None of the above
Ans : 3

4. If biasing is not done in an amplifier circuit, it results in ……………
1.Decrease in the base current
2.Unfaithful amplification
3.Excessive collector bias
4.None of the above
Ans : 2

5. Transistor biasing is generally provided by a …………….
1.Biasing circuit
2.Bias battery
3.Diode
4.None of the above
Ans : 1

6. For faithful amplification by a transistor circuit, the value of VBE should ………. for a silicon transistor
1.Be zero
2.Be 0.01 V
3.Not fall below 0.7 V
4.Be between 0 V and 0.1 V
Ans : 3

7. For proper operation of the transistor, its collector should have …………
1.Proper forward bias
2.Proper reverse bias
3.Very small size
4.None of the above
Ans : 2

8. For faithful amplification by a transistor circuit, the value of VCE should ……….. for silicon transistor
1.Not fall below 1 V
2.Be zero
3.Be 0.2 V
4.None of the above
Ans : 1

9. The circuit that provides the best stabilization of operating point is …………
1.Base resistor bias
2.Collector feedback bias
3.Potential divider bias
4.None of the above
Ans : 3

10. The point of intersection of d.c. and a.c. load lines represents …………..
1.Operating point
2.Current gain
3.Voltage gain
4.None of the above
Ans : 1

11. An ideal value of stability factor is …………..
1.100
2.200
3.More than 200
4.1
Ans : 4

12. The zero signal IC is generally ……………… mA in the initial stages of a transistor amplifier
1.4
2.1
3.3
4.More than 10
Ans : 2

13. If the maximum collector current due to signal alone is 3 mA, then zero signal collector current should be at least equal to ………..
1.6 mA
2.mA
3.3 mA
4.1 mA
Ans : 3

14. The disadvantage of base resistor method of transistor biasing is that it …………
1.Is complicated
2.Is sensitive to changes in ß
3.Provides high stability
4.None of the above
Ans : 2

15. The biasing circuit has a stability factor of 50. If due to temperature change, ICBO changes by 1 µA, then IC will change by …………
1.100 µA
2.25 µA
3.20 µA
4.50 µA
Ans : 4

16. For good stabilsation in voltage divider bias, the current I1 flowing through R1 and R2 should be equal to or greater than
1.10 IB
2.3 IB
3.2 IB
4.4 IB
Ans : 1

17. The leakage current in a silicon transistor is about ………… the leakage current in a germanium transistor
1.One hundredth
2.One tenth
3.One thousandth
4.One millionth
Ans : 3

18. The operating point is also called the ………….
1.Cut off point
2.Quiescent point
3.Saturation point
4.None of the above
Ans : 2

19. For proper amplification by a transistor circuit, the operating point should be located at the ………….. of the d.c. load line
1.The end point
2.Middle
3.The maximum current point
4.None of the above
Ans : 2

20. The operating point ………………… on the a.c. load line
1.Also line
2.Does not lie
3.May or may not lie
4.Data insufficient
Ans : 1

21. The disadvantage of voltage divider bias is that it has ………….
1.High stability factor
2.Low base current
3.Many resistors
4.None of the above
Ans : 3

22. Thermal runaway occurs when ……….
1.Collector is reverse biased
2.Transistor is not biased
3.Emitter is forward biased
4.Junction capacitance is high
Ans : 2

23. The purpose of resistance in the emitter circuit of a transistor amplifier is to ………….
1.Limit the maximum emitter current
2.Provide base-emitter bias
3.Limit the change in emitter current
4.None of the above
Ans : 3

24. In a transistor amplifier circuit VCE = VCB + ……………..
1.VBE
2.2VBE
3.5 VBE
4.None of the above
Ans : 1

25. The base resistor method is generally used in ………
1.Amplifier circuits
2.Switching circuits
3.Rectifier circuits
4.None of the above
Ans : 2

26. For germanium transistor amplifier, VCE should ………….. for faithful amplification
1.Be zero
2.Be 0.2 V
3.Not fall below 0.7 V
4.None of the above
Ans : 3

27. In a base resistor method, if the value of ß changes by 50, then collector current will change by a factor ………
1.25
2.50
3.100
4.200
Ans : 2

28. The stability factor of a collector feedback bias circuit is ……….. that of base resistor bias.
1.The same as
2.More than
3.Less than
4.None of the above
Ans : 3

29. In the design of a biasing circuit, the value of collector load RC is determined by …………
1.VCE consideration
2.VBE consideration
3.IB consideration
4.None of the above
Ans : 1

30. If the value of collector current IC increases, then the value of VCE …………
1.Remains the same
2.Decreases
3.Increases
4.None of the above
Ans : 2

31. If the temperature increases, the value of VCE …………
1.Remains the same
2.Is increased
3.Is decreased
4.None of the above
Ans : 3

32. The stabilisation of operating point in potential divider method is provided by ……….
1.RE consideration
2.RC consideration
3.VCC consideration
4.None of the above
Answer: 1

33. The value of VBE …………….
1.Depends upon IC to moderate extent
2.Is almost independent of IC
3.Is strongly dependant on IC
4.None of the above
Ans : 2

34. When the temperature changes, the operating point is shifted due to …….
1.Change in ICBO
2.Change in VCC
3.Change in the values of circuit resistance
4.None of the above
Ans : 1

35. The value of stability factor for a base resistor bias is …………
1.RB (ß+1)
2.(ß+1)RC
3.(ß+1)
4.1-ß
Ans : 3

36. In a particular biasing circuit, the value of RE is about ………
1.10 kO
2.1 MO
3.100 kO
4.800 O
Ans : 4

37. A silicon transistor is biased with base resistor method. If ß=100, VBE =0.7 V, zero signal collector current IC = 1 mA and VCC = 6V , what is the value of the base resistor RB?
1.105 kO
2.530 kO
3.315 kO
4.None of the above
Ans : 2

38. In voltage divider bias, VCC = 25 V; R1 = 10 kO; R2 = 2.2 V ; RC = 3.6 V and RE =1 kO. What is the emitter voltage?
1.7 V
2.3 V
3.V
4.8 V
Ans : 4

39. In the above question (Q38.) , what is the collector voltage?
1.3 V
2.8 V
3.6 V
4.7 V
Ans : 1

40. In voltage divider bias, operating point is 3 V, 2 mA. If VCC = 9 V, RC = 2.2 kO, what is the value of RE ?
1.2000 O
2.1400 O
3.800 O
4.1600 O
Ans :3

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