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. 0º
- 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 transistors 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