Bipolar Junction Transistors (Bjt) MCQs

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A collector characteristic curve is a graph showing:

  • A. emitter current (IE) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant
  • B. collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held constant
  • C. collector current (IC) versus collector-emitter voltage (VC) with (VBB) base bias voltage held constant
  • D. collector current (IC) versus collector-emitter voltage (VCC) with (VBB) base bias voltage held constant
  • Correct Answer: Option B

A current ratio of IC/IE is usually less than one and is called:

  • A. beta
  • B. theta
  • C. alpha
  • D. omega
  • Correct Answer: Option C

A transistor may be used as a switching device or as a:

  • A. fixed resistor
  • B. tuning device
  • C. rectifier
  • D. variable resistor
  • Correct Answer: Option D

An emitter-follower has a voltage gain that is __________.

  • A. much less than one
  • B. approximately equal to one
  • C. greater than one
  • D. zero
  • Correct Answer: Option B

Base bias provides _________.

  • A. a very stable Q point
  • B. a very unstable Q point
  • C. no current gain
  • D. zero current in the base and collector circuits
  • Correct Answer: Option B

For a C-C configuration to operate properly, the collector-base junction should be reverse biased, while forward bias should be applied to which junction?

  • A. collector-emitter
  • B. base-emitter
  • C. collector-base
  • D. cathode-anode
  • Correct Answer: Option A

If a 2 mV signal produces a 2 V output, what is the voltage gain?

  • A. 0.001
  • B. 0.004
  • C. 100
  • D. 1000
  • Correct Answer: Option D

If a transistor operates at the middle of the dc load line, a decrease in the current gain will move the Q point:

  • A. off the load line
  • B. nowhere
  • C. up
  • D. down
  • Correct Answer: Option D

If an input signal ranges from 20–40 A (microamps), with an output signal ranging from .5–1.5 mA (milliamps), what is the ac beta?

  • A. 0.05
  • B. 20
  • C. 50
  • D. 500
  • Correct Answer: Option C

If VCC = +18 V, voltage-divider resistor R1 is 4.7 k, and R2 is 1500, what is the base bias voltage?

  • A. 8.70 V
  • B. 4.35 V
  • C. 2.90 V
  • D. 0.7 V
  • Correct Answer: Option B

In a C-E configuration, an emitter resistor is used for:

  • A. stabilization
  • B. ac signal bypass
  • C. collector bias
  • D. higher gain
  • Correct Answer: Option A

In a transistor, collector current is controlled by:

  • A. collector voltage
  • B. base current
  • C. collector resistance
  • D. all of the above
  • Correct Answer: Option B

Most of the electrons in the base of an NPN transistor flow:

  • A. out of the base lead
  • B. into the collector
  • C. into the emitter
  • D. into the base supply
  • Correct Answer: Option B

Often a common-collector will be the last stage before the load; the main function(s) of this stage is to:

  • A. provide voltage gain
  • B. provide phase inversion
  • C. provide a high-frequency path to improve the frequency response
  • D. buffer the voltage amplifiers from the low-resistance load and provide impedance matching for maximum power transfer
  • Correct Answer: Option D

The C-B configuration is used to provide which type of gain?

  • A. voltage
  • B. current
  • C. resistance
  • D. power
  • Correct Answer: Option A

The ends of a load line drawn on a family of curves determine:

  • A. saturation and cutoff
  • B. the operating point
  • C. the power curve
  • D. the amplification factor
  • Correct Answer: Option A

The input resistance of the base of an emitter-follower is usually _________.

  • A. very low
  • B. very high
  • C. shorted to ground
  • D. open
  • Correct Answer: Option B

The input/output relationship of the common-collector and common-base amplifiers is:

  • A. 270 degrees
  • B. 180 degrees
  • C. 90 degrees
  • D. 0 degrees
  • Correct Answer: Option D

The phase difference between the input and output ac voltage signals of a common-emitter amplifier is __________.

  • A.
  • B. 90º
  • C. 180º
  • D. 360º
  • Correct Answer: Option C

The Q point on a load line may be used to determine:

  • A. VC
  • B. VCC
  • C. VB
  • D. IC
  • Correct Answer: Option C

Three different Q points are shown on a dc load line. The upper Q point represents the:

  • A. minimum current gain
  • B. intermediate current gain
  • C. maximum current gain
  • D. cutoff point
  • Correct Answer: Option C

To operate properly, a transistor’s base-emitter junction must be forward biased with reverse bias applied to which junction?

  • A. collector-emitter
  • B. base-collector
  • C. base-emitter
  • D. collector-base
  • Correct Answer: Option D

Total emitter current is:

  • A. IE – IC
  • B. IC + IE
  • C. IB + IC
  • D. IB – IC
  • Correct Answer: Option C

VCE approximately equals ________ when a transistor switch is cut off.

  • A. VCC
  • B. VB
  • C. 0.2 V
  • D. 0.7 V
  • Correct Answer: Option A

VCE approximately equals ________ when a transistor switch is in saturation.

  • A. VC
  • B. VB
  • C. 0.3 V
  • D. 0.7 V
  • Correct Answer: Option C

Voltage-divider bias provides:

  • A. an unstable Q point
  • B. a stable Q point
  • C. a Q point that easily varies with changes in the transistor's current gain
  • D. a Q point that is stable and easily varies with changes in the transistor’s current gain
  • Correct Answer: Option B

What is the collector current for a C-E configuration with a beta of 100 and a base current of 30 A?

  • A. 30 A
  • B. .3 A
  • C. 3 mA
  • D. 3 MA
  • Correct Answer: Option C

What is the current gain for a common-base configuration where IE = 4.2 mA and IC = 4.0 mA?

  • A. 16.80
  • B. 1.05
  • C. 0.20
  • D. 0.95
  • Correct Answer: Option D

When a silicon diode is forward biased, what is VBE for a C-E configuration?

  • A. voltage-divider bias
  • B. 0.4 V
  • C. 0.7 V
  • D. emitter voltage
  • Correct Answer: Option C

When transistors are used in digital circuits they usually operate in the:

  • A. active region
  • B. breakdown region
  • C. saturation and cutoff regions
  • D. linear region
  • Correct Answer: Option C

Which is beta’s current ratio?

  • A. IC/IB
  • B. IC/IE
  • C. IB/IE
  • D. IE/IB
  • Correct Answer: Option A

Which is the higher gain provided by a C-E configuration?

  • A. voltage
  • B. current
  • C. resistance
  • D. power
  • Correct Answer: Option D

With a PNP circuit, the most positive voltage is probably:

  • A. ground
  • B. VC
  • C. VBE
  • D. VCC
  • Correct Answer: Option A

With low-power transistor packages, the base terminal is usually the:

  • A. tab end
  • B. middle
  • C. right end
  • D. stud mount
  • Correct Answer: Option B

With the positive probe on an NPN base, an ohmmeter reading between the other transistor terminals should be:

  • A. open
  • B. infinite
  • C. low resistance
  • D. high resistance
  • Correct Answer: Option C