# Bipolar Junction Transistors (BJT) MCQ Questions & Answers

Bipolar Junction Transistors (BJT) MCQs : This section focuses on the "Bipolar Junction Transistors (BJT)". These Multiple Choice Questions (MCQs) should be practiced to improve the Bipolar Junction Transistors (BJT) skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

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

A. 16.8
B. 1.05
C. 0.2
D. 0.95

Question 2

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

Question 3

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

Question 4

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

Question 5

In a transistor, collector current is controlled by:

A. collector voltage
B. base current
C. collector resistance
D. all of the above

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

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

Question 13

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

Question 14

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

A. stabilization
B. ac signal bypass
C. collector bias
D. higher gain

Question 15

Total emitter current is:

A. IE – IC
B. IC + IE
C. IB + IC
D. IB – IC

Question 16

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

A. VC
B. VCC
C. VB
D. IC

Question 17

Which is beta's current ratio?

A. IC/IB
B. IC/IE
C. IB/IE
D. IE/IB

Question 18

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

Question 19

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

Question 20

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

A. beta
B. theta
C. alpha
D. omega

Question 21

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

A. voltage
B. current
C. resistance
D. power

Question 22

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

A. voltage
B. current
C. resistance
D. power

Question 23

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

A. tab end
B. middle
C. right end
D. stud mount

Question 24

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

Question 25

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

A. fixed resistor
B. tuning device
C. rectifier
D. variable resistor

Question 26

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

A. ground
B. VC
C. VBE
D. VCC