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Syllabus

NEC Electronics · Practice

Chapters & sets

1. Basic Electrical and Electronics Engineering

Basic Electrical

Set 1106

Basic Electronics

Set 171 Set 233

2. Digital Logic and Microprocessor

Digital Logic

Set 150 Set 250 Set 350 Set 450 Set 550 Set 650 Set 749 Set 851 Set 950 Set 1050 Set 1150 Set 1232

Microprocessor

Set 150 Set 250 Set 350 Set 445 Set 550 Set 650 Set 720 Set 850 Set 969

3. Programming Language and Its Applications

Mixed chapter MCQs

Set 150 Set 249 Set 349 Set 451 Set 540

4. Computer Organization and Embedded Systems

Mixed chapter MCQs

Set 150 Set 249 Set 350 Set 450 Set 550 Set 650 Set 750 Set 849 Set 950 Set 1050 Set 1150

5. Computer Networks and Network Security

Basic Networking

Set 150 Set 253

Advanced Networking

Set 150 Set 250 Set 350 Set 450 Set 550 Set 655

10. Project Planning, Design and Implementation

Basic Electronics Set 1

71 questions

Question 1

How does a semiconductor behave at absolute zero?

A.
Conductor
B.
Insulator
C.
Semiconductor
D.
Protection device

Question 2

Semiconductor acts as an insulator in the presence of impurities.

A.
True
B.
False

Question 3

How is the resistance of semiconductor classified?

A.
High resistance
B.
Positive temperature co-efficient
C.
Negative temperature co-efficient
D.
Low resistance

Question 4

What are the charge carriers in semiconductors?

A.
Electrons and holes
B.
Electrons
C.
Holes
D.
Charges

Question 5

What type of material is obtained when an intrinsic semiconductor is doped with pentavalent impurity?

A.
N-type semiconductor
B.
Extrinsic semiconductor
C.
P-type semiconductor
D.
Insulator

Question 6

What type of material is obtained when an intrinsic semiconductor is doped with trivalent impurity?

A.
Extrinsic semiconductor
B.
Insulator
C.
N-type semiconductor
D.
P-type semiconductor

Question 7

When a pure semiconductor is heated, its resistance ______.

A.
Goes up
B.
Goes down
C.
Remains the same
D.
Can't say

Question 8

As the doping to a pure semiconductor increases, the bulk resistance of the semi-conductor ______.

A.
Remains the same
B.
Increases
C.
Decreases
D.
None of the above

Question 9

The reverse current in a diode is of the order of ______.

A.
kA
B.
mA
C.
μA
D.
A

Question 10

The forward voltage drop across a silicon diode is about ______.

A.
2.5 V
B.
3 V
C.
10 V
D.
0.7 V

Question 11

A zener diode has ______.

A.
One pn junction
B.
Two pn junctions
C.
Three pn junctions
D.
None of the above

Question 12

A zener diode is used as ______.

A.
An amplifier
B.
A voltage regulator
C.
A rectifier
D.
A multivibrator

Question 13

Why is there a sudden increase in current in Zener diode?

A.
Due to the rupture of ionic bonds
B.
Due to rupture of covalent bonds
C.
Due to viscosity
D.
Due to potential difference

Question 14

What is the semiconductor diode used as?

A.
Oscillator
B.
Amplifier
C.
Rectifier
D.
Modulator

Question 15

What is a Zener diode used as?

A.
Oscillator
B.
Regulator
C.
Rectifier
D.
Filter

Question 16

When a junction diode is reverse biased, what causes current across the junction?

A.
Diffusion of charges
B.
Nature of material
C.
Drift of charges
D.
Both drift and diffusion of charges

Question 17

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

A.
Active region
B.
Saturation and cutoff regions
C.
Breakdown region
D.
Linear region

Question 18

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

A.
Alpha
B.
Beta
C.
Theta
D.
None of above

Question 19

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

A.
Stabilization
B.
Ac signal bypass
C.
Collector bias
D.
Higher gain

Question 20

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 21

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

A.
Voltage
B.
Current
C.
Resistance
D.
Power

Question 22

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

A.
Fixed resistor
B.
Tuning device
C.
Rectifier
D.
Variable resistor

Question 23

Which is beta’s current ratio?

A.
$\frac{I_C}{I_B}$
B.
$\frac{I_C}{I_E}$
C.
$\frac{I_B}{I_E}$
D.
$\frac{I_E}{I_B}$

Question 24

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 25

In a transistor, collector current is controlled by:

A.
Collector voltage
B.
Base current
C.
Collector resistance
D.
All of the above

Question 26

Total emitter current is:

A.
$I_E - I_C$
B.
$I_C + I_E$
C.
$I_B + I_C$
D.
$I_B - I_C$

Question 27

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

A.
30 μA
B.
3 μA
C.
3 mA
D.
3 MA

Question 28

Which of the following condition is true for cut-off mode?

A.
The collector current is zero
B.
The collector current is proportional to the base current
C.
The base current is non zero
D.
All of the mentioned

Question 29

For a pnp transistor in the active region the value of Vcc (potential difference between the collector and the base) is:

A.
Less than 0.3V
B.
Less than 3V
C.
Greater than 0.3V
D.
Greater than 3V

Question 30

Where should be the bias point set in order to make transistor work as an amplifier?

A.
Cut off
B.
Active
C.
Saturation
D.
Cut off and Saturation

Question 31

Q point can be set to work on active region requires particular conditions. What are they?

A.
BE reverse biased and BC forward biased
B.
BE reverse biased and BC reverse biased
C.
BE forward biased and BC reverse biased
D.
BE forward biased and BC forward biased

Question 32

For a fixed bias circuit having RC=4.7kΩ and RB=1kΩ, VCC=10V, and base current at Bias point was found to be 0.2μA, Find β?

A.
100
B.
106
C.
125
D.
0

Question 33

For a Voltage divider bias circuit, having R1=R2=10kΩ, RC=4.7 kΩ, RE=1 kΩ, What is the value of collector current at saturation if VCC=10V?

A.
1A
B.
10mA
C.
0.87mA
D.
1mA

Question 34

For a Voltage divider circuit having RC=R1=R2=RE=1kΩ, if VCC=20V, find IC when Vcc = VCC?

A.
1mA
B.
2mA
C.
20mA
D.
0

Question 35

What is Stability factor?

A.
Ratio of change in collector current to change in a current amplification factor
B.
Ratio of change in collector current to change in base current
C.
Current amplification factor
D.
Ratio of base current to collector current

Question 36

The collector current (IC. that is obtained in a collector to base biased transistor is ______.

A.
$\frac{V_{CC} - V_{BE}}{R_B}$
B.
$\frac{V_{CC} + V_{BE}}{R_B}$
C.
$\frac{V_{CE} - V_{BE}}{R_B}$
D.
$\frac{V_{CE} + V_{BE}}{R_B}$

Question 37

The demerit of a collector to base bias is ______.

A.
Its need of high resistance values
B.
Its dependence on β
C.
Its independence on β
D.
The positive feedback produced by the base resistor

Question 38

For emitter feedback bias, to make IC independent of DC current gain, which of the following condition is required?

A.
$R_C >> \frac{R_B}{\beta}$
B.
$R_E >> \frac{R_B}{\beta}$
C.
$R_B >> \frac{R_C}{\beta}$
D.
$R_E >> \frac{R_C}{\beta}$

Question 39

In order to make an amplifier which of the following biasing technique is used more?

A.
Fixed bias
B.
Self bias
C.
Collector to base bias
D.
Emitter feedback bias

Question 40

What will be the temperature changes effects on the emitter feedback circuit?

A.
Increases voltage gain
B.
Increases current gain
C.
Does not affect the gain
D.
Decreases both current and voltage gain

Question 41

Which of the following statement is the main disadvantage of emitter feedback bias?

A.
Reduces the gain
B.
Positive feedback
C.
Design is difficult
D.
High output impedance

Question 42

The thermal runway is avoided in a self-bias because ______.

A.
of its independence of β
B.
of the positive feedback produced by the emitter resistor
C.
of the negative feedback produced by the emitter resistor
D.
of its dependence of β

Question 43

The stability factor for a self-biased transistor is ______.

A.
$1 - \frac{R_{TH}}{R_E}$
B.
$1 + \frac{R_{TH}}{R_E}$
C.
$1 + \frac{R_E}{R_{TH}}$
D.
$1 - \frac{R_E}{R_{TH}}$

Question 44

Which of the following terminals does not belong to the MOSFET?

A.
Drain
B.
Gate
C.
Base
D.
Source

Question 45

Choose the correct statement:

A.
MOSFET is an uncontrolled device
B.
MOSFET is a voltage controlled device
C.
MOSFET is a current controlled device
D.
MOSFET is a temperature controlled device

Question 46

Choose the correct statement:

A.
MOSFET is a unipolar, voltage controlled, two terminal device
B.
MOSFET is a bipolar, current controlled, three terminal device
C.
MOSFET is a unipolar, voltage controlled, three terminal device
D.
MOSFET is a bipolar, current controlled, two terminal device

Question 47

The controlling parameter in MOSFET is:

A.
$V_{DS}$
B.
$I_G$
C.
$V_{GS}$
D.
$I_S$

Question 48

How does the MOSFET differ from the JFET?

A.
JFET has a p-n junction
B.
They are both the same
C.
JFET is small in size
D.
MOSFET has a base terminal

Question 49

The N-channel MOSFET is considered better than the P-channel MOSFET due to its:

A.
Low noise levels
B.
TTL compatibility
C.
Lower input impedance
D.
Faster operation

Question 50

Which factor/s play/s a crucial role in determining the speed of CMOS logic gate?

A.
Load capacitance
B.
Supply voltage
C.
Gain factor of MOS
D.
All of the above

Question 51

What will be the phase shift of feedback circuit in RC phase shift oscillator?

A.
360° phase shift
B.
180° phase shift
C.
90° phase shift
D.
60° phase shift

Question 52

How many RC stages are used in the RC phase shift oscillator?

A.
Six
B.
Two
C.
Four
D.
Three

Question 53

Calculate the frequency of oscillation for RC phase shift oscillator having the value of R and C as 35Ω and 3.7μF respectively.

A.
1230 Hz
B.
204 Hz
C.
502 Hz
D.
673 Hz

Question 54

The condition for zero phase shift in wein bridge oscillator is achieved by:

A.
Connecting feedback to non-inverting input terminal of op-amp
B.
Balancing the bridge
C.
Applying parallel combination of RC to the feedback network
D.
All of the mentioned

Question 55

Only the condition

\beta A = \underline{\qquad}

must be satisfied for self-sustained oscillations to result.

A.
0
B.
-1
C.
1
D.
None of the above

Question 56

This circuit is a ______ oscillator.

Diagram unavailable; refer to the source page.

A.
Phase-shift
B.
Wien bridge
C.
Colpitts
D.
Hartley

Question 57

The feedback signal in a(n) ______ oscillator is derived from an inductive voltage divider in the LC circuit.

A.
Hartley
B.
Armstrong
C.
Colpitts
D.
All of the above

Question 58

For a phase-shift oscillator, the gain of the amplifier stage must be greater than ______.

A.
19
B.
29
C.
30
D.
1

Question 59

What is the minimum frequency at which a crystal will oscillate?

A.
Seventh harmonic
B.
Third harmonic
C.
Fundamental
D.
Second harmonic

Question 60

This circuit is a ______ oscillator.

Diagram unavailable; refer to the source page.

A.
Phase-shift
B.
Wien bridge
C.
Colpitts
D.
Hartley

Question 61

How a triangular wave generator is derived from square wave generator?

A.
Connect oscillator at the output
B.
Connect Voltage follower at the output
C.
Connect differential at the output
D.
Connect integrator at the output

Question 62

Output of an integrator producing waveforms of unequal rise and fall time are called:

A.
Triangular waveform
B.
Sawtooth waveform
C.
Pulsating waveform
D.
Spiked waveform

Question 63

Which of the following is required for oscillation?

A.
$\beta A > 1$
B.
The phase shift around the feedback network must be 180°
C.
Both $\beta A > 1$ and the phase shift around the feedback network must be 180°
D.
None of the above

Question 64

An oscillator converts ______.

A.
DC power into AC power
B.
AC power into DC power
C.
Mechanical power into AC power
D.
None of the above

Question 65

In an LC transistor oscillator, the active device is ______.

A.
LC tank circuit
B.
Biasing circuit
C.
Transistor
D.
None of the above

Question 66

In an LC circuit, when the capacitor is maximum, the inductor energy is ______.

A.
Minimum
B.
Maximum
C.
Half-way between maximum and minimum
D.
None of the above

Question 67

In an LC oscillator, the frequency of oscillator is ______ L or C.

A.
Proportional to square of
B.
Directly proportional to
C.
Independent of the values of
D.
Inversely proportional to square root of

Question 68

An oscillator produces ______ oscillations.

A.
Damped
B.
Undamped
C.
Modulated
D.
None of the above

Question 69

An oscillator employs ______ feedback.

A.
Positive
B.
Negative
C.
Neither positive nor negative
D.
Data insufficient

Question 70

Hartley oscillator is commonly used in ______.

A.
Radio receivers
B.
Radio transmitters
C.
TV receivers
D.
None of the above

Question 71

In a phase shift oscillator, we use ______ RC sections.

A.
Two
B.
Three
C.
Four
D.
None of the above

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