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Sunday, April 6, 2014

Bipolar Junction Transistors – MCQs

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MCQs for Bipolar Junction Transistors

Multiple Choice Questions Topic Outline

  • MCQs in Transistor Construction
  • MCQs in Transistor Operation
  • MCQs in Common-Base Configuration
  • MCQs in Transistor Amplifying Action
  • MCQs in Common-Emitter Configuration
  • MCQs in Common-Collector Configuration
  • MCQs in Limits of Operation
  • MCQs in Transistor Specification Sheet
  • MCQs in Transistor Testing
  • MCQs in Transistor Casing and Terminal Identification

Begin and Good luck!

1. In what decade was the first transistor created?

  • A)    1930s
  • B)    1940s
  • C)    1950s
  • D)    1960s

2. How many layers of material does a transistor have?

  • A)    1
  • B)    2
  • C)    3
  • D)    4

3. What is the ratio of the total width to that of the center layer for a transistor?

  • A)    1:15
  • B)    1:150
  • C)    15:1
  • D)    150:1

4. Which of the following is (are) the terminal(s) of a transistor?

  • A)    Emitter
  • B)    Base
  • C)    Collector
  • D)    All of the above

5. List the types of bipolar junction transistors.

  • A)    ppn, npn
  • B)    pnp, npn
  • C)    npp, ppn
  • D)    nnp, pnp

6. Transistors are _____-terminal devices.

  • A)    2
  • B)    3
  • C)    4
  • D)    5

7. How many carriers participate in the injection process of a unipolar device?

  • A)    1
  • B)    2
  • C)    0
  • D)    3

8. Which component of the collector current IC is called the leakage current?

  • A)    Majority
  • B)    Independent
  • C)    Minority
  • D)    None of the above

9. For a properly biased pnp transistor, let IC = 10 mA and IE = 10.2 mA. What is the level of IB?

  • A)    0.2 A
  • B)    200 mA
  • C)    200 µA
  • D)    20.2 mA

10. Calculate minority current ICO if IC = 20.002 mA and IC majority = 20 mA.

  • A)    2 µA
  • B)    0.002 µA
  • C)    2 nA
  • D)    2 pA

11. Which of the following regions is (are) part of the output characteristics of a transistor?

  • A)    Active
  • B)    Cutoff
  • C)    Saturation
  • D)    All of the above

12. In which region are both the collector-base and base-emitter junctions forward-biased?

  • A)    Active
  • B)    Cutoff
  • C)    Saturation
  • D)    All of the above

13. How much is the base-to-emitter voltage of a transistor in the "on" state?

  • A)    0 V
  • B)    0.7 V
  • C)    0.7 mV
  • D)    Undefined

14. In the active region, while the collector-base junction is _____-biased, the base-emitter is _____-biased.

  • A)    forward, forward
  • B)    forward, reverse
  • C)    reverse, forward
  • D)    reverse, reverse

15. What is βdc equal to?

  • A)    IB / IE
  • B)    IC / IE
  • C)    IC / IB
  • D)    None of the above

16. What are the ranges of the ac input and output resistance for a common-base configuration?

  • A)    10 Ω–100 Ω, 50 k Ω–1 MΩ
  • B)    50 kΩ –1 MΩ, 10 Ω –100 Ω
  • C)    10 Ω –100 kΩ, 50 Ω –1 kΩ
  • D)    None of the above

17. For what kind of amplifications can the active region of the common-emitter configuration be used?

  • A)    Voltage
  • B)    Current
  • C)    Power
  • D)    All of the above

18. Use this table of collector characteristics to calculate βac at VCE = 15 V and IB = 30 µA.

MCQs in Bipolar Junction Transistors Fig. 01

  • A)    100
  • B)    106
  • C)    50
  • D)    400

19. Calculate βdc at VCE = 15 V and IB = 30 µA.

MCQs in Bipolar Junction Transistors Fig. 02

  • A)    100
  • B)    116
  • C)    50
  • D)    110

20. Which of the following configurations can a transistor set up?

  • A)    Common-base
  • B)    Common-emitter
  • C)    Common-collector
  • D)    All of the above

21. Determine the value of α when β = 100.

  • A)    1.01
  • B)    101
  • C)    0.99
  • D)    Cannot be solved with the information provided

22. What is the most frequently encountered transistor configuration?

  • A)    Common-base
  • B)    Common-collector
  • C)    Common-emitter
  • D)    Emitter-collector

23. βdc for this set of collector characteristics is within _____ percent of βac.

MCQs in Bipolar Junction Transistors Fig. 03

  • A)    2
  • B)    5
  • C)    7
  • D)    10

24. βdc = ________

  • A)    IB / IE
  • B)    IC / IE
  • C)    IC / IB
  • D)    None of the above

25. What is (are) the component(s) of most specification sheets provided by the manufacturer?

  • A)    Maximum ratings
  • B)    Thermal characteristics
  • C)    Electrical characteristics
  • D)    All of the above

26. What is (are) the component(s) of electrical characteristics on the specification sheets?

  • A)    On
  • B)    Off
  • C)    Small-signal characteristics
  • D)    All of the above

27. Most specification sheets are broken down into _____.

  • A)    maximum ratings
  • B)    thermal characteristics
  • C)    electrical characteristics
  • D)    All of the above

28. An example of a pnp silicon transistor is a 2N4123.

  • A)    True
  • B)    False

29. Which of the following equipment can check the condition of a transistor?

  • A)    Current tracer
  • B)    Digital display meter (DDM)
  • C)    Ohmmeter (VOM)
  • D)    All of the above

30. Which of the following can be obtained from the last scale factor of a curve tracer?

  • A)    hFE
  • B)    αdc
  • C)    αac
  • D)    βac

31. Calculate βac for IC = 15 mA and VCE = 5 V.

MCQs in Bipolar Junction Transistors Fig. 04

  • A)    200
  • B)    180
  • C)    220
  • D)    None of the above

32. What range of resistor values would you get when checking a transistor for forward- and reverse-biased conditions by an ohmmeter?

  • A)    100 Ω to a few kΩ, exceeding 100 kΩ
  • B)    Exceeding 100 kΩ, 100 Ω to a few kΩ
  • C)    Exceeding 100 kΩ, exceeding 100 kΩ
  • D)    100 Ω to a few kΩ, 100 Ω to a few kΩ

33. What does a reading of a large or small resistance in forward- and reverse-biased conditions indicate when checking a transistor using an ohmmeter?

  • A)    Faulty device
  • B)    Good device
  • C)    Bad ohmmeter
  • D)    None of the above

34. A transistor can be checked using a(n) _____.

  • A)    curve tracer
  • B)    digital meter
  • C)    ohmmeter
  • D)    Any of the above

35. How many individual pnp silicon transistors can be housed in a 14-pin plastic dual-in-line package?

  • A)    4
  • B)    7
  • C)    10
  • D)    14

Fill-in-the-blanks Questions

1. All amplifiers should have at least _____ terminals with _____ terminal(s) controlling the flow between _____ other terminal(s).

  • A)    2, 1, 1
  • B)    3, 1, 2
  • C)    3, 2, 1
  • D)    3, 0, 3

2. The outer layers of a transistor are _____ the sandwiched layer.

  • A)    much smaller than
  • B)    the same as
  • C)    much larger than
  • D)    None of the above

3. The doping of the sandwiched layer is _____ that of the outer layers.

  • A)    considerably less than
  • B)    the same as
  • C)    considerably more than
  • D)    None of the above

4. The lower doping level _____ the conductivity and _____ the resistivity of the material.

  • A)    increases, decreases
  • B)    increases, increases
  • C)    decreases, decreases
  • D)    decreases, increases

5. The term bipolar reflects the fact that _____ and _____ participate in the injection process into the oppositely polarized material.

  • A)    holes, neutrons
  • B)    holes, electrons
  • C)    neutrons, electrons
  • D)    None of the above

6. One p-n junction of a transistor is _____-biased and the other one is _____-biased in the active region.

  • A)    reverse, reverse
  • B)    forward, forward
  • C)    reverse, forward
  • D)    None of the above

7. The magnitude of the base current is typically on the order of _____ as compared to _____ for the emitter.

  • A)    µA, µA
  • B)    µA, mA
  • C)    mA, µA
  • D)    mA, mA

8. The base current is the _____ of the emitter and collector currents.

  • A)    sum
  • B)    difference
  • C)    product
  • D)    None of the above

9. The _____ region is the region normally employed for linear (undistorted) amplifiers.

  • A)    active
  • B)    cutoff
  • C)    saturation
  • D)    All of the above

10. In the cutoff region the collector-base junction is _____-biased and the base-emitter junction is _____-biased for a transistor.

  • A)    reverse, forward
  • B)    forward, reverse
  • C)    reverse, reverse
  • D)    forward, forward

11. In the saturation region the collector-base junction is _____-biased and the base-emitter junction is _____-biased for a transistor.

  • A)    reverse, forward
  • B)    forward, reverse
  • C)    reverse, reverse
  • D)    forward, forward

12. For practical transistors the level of alpha typically extends from _____ to _____ with most approaching the higher end of the range.

  • A)    0.0, 1
  • B)    0.90, 0.998
  • C)    50, 400
  • D)    None of the above

13. Typical values of voltage amplification for the common-base configurations vary from _____ and the current gain is always _____ .

  • A)    less than 1, 50 to 300
  • B)    50 to 300, larger than 1
  • C)    50 to 300, less than 1
  • D)    larger than 1, 50 to 300

14. If a value of beta.gif is specified for a particular transistor configuration it will normally be used for _____ calculations.

  • A)    ac
  • B)    dc
  • C)    ac and dc
  • D)    None of the above

15. The common-collector configuration has a _____ input impedance and a _____ output impedance.

  • A)    low, high
  • B)    high, low
  • C)    high, high
  • D)    low, low

16. The active region of a transistor is bounded by the _____.

  • A)    cutoff region
  • B)    saturation region
  • C)    power dissipation curve
  • D)    All of the above

17. The "on" and "off" characteristics refer to _____ limits while the small-signal characteristics indicate the parameters of importance to _____ operation.

  • A)    ac, dc
  • B)    dc, ac
  • C)    ac, dc and ac
  • D)    dc and ac, dc

18. The step function (per step) of a curve tracer reveals the scale for _____.

  • A)    collector current IC
  • B)    VCE voltage
  • C)    base current IB
  • D)    All of the above

19. The level of _____ is determined and displayed by advanced digital meters.

  • A)    VCE
  • B)    IB
  • C)    IC
  • D)    βdc

20. The level of _____ is determined and displayed by advanced digital meters if using diode-testing mode.

  • A)    VBE
  • B)    IC
  • C)    IB
  • D)    IE

21. When checking a transistor by ohmmeter, a relatively _____ resistance is displayed for a forward-biased junction and _____ resistance for a reverse-biased junction.

  • A)    low, very high
  • B)    low, low
  • C)    high, high
  • D)    high, very low

22. An OL indication on an advanced digital meter indicates _____ while checking a transistor.

  • A)    forward bias
  • B)    reverse bias
  • C)    definitely a defective transistor
  • D)    None of the above

23. If the positive lead of an ohmmeter is connected to the base and the negative lead to the emitter, a low resistance reading would indicate a _____ transistor and a high resistance reading would indicate a _____ transistor.

  • A)    npn, pnp
  • B)    pnp, npn
  • C)    npn, npn
  • D)    pnp, pnp

24. The leads of a transistor are typically made of _____.

  • A)    gold
  • B)    aluminum
  • C)    nickel
  • D)    All of the above

25. There is(are) _____ in the internal construction of a TO-92 package.

  • A)    gold bond wires
  • B)    a copper frame
  • C)    epoxy encapsulation
  • D)    All of the above

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