At temperature of 298 Kelvin, Silicon is not suitable for most-electronic applications, due to small amount of conductivity. This can be altered by
A
Gettering
B
Doping
C
Squeezing
D
Sintering
Question 2Single Answer
By doping Germanium with Gallium, the types of semi-conductors formed are
1. N type
2. P type
3. Intrinsic
4. Extrinsic
A
1 and 4
B
2 and 4
C
1 and 3
D
2 and 3
Question 3Single Answer
An n-type of silicon can be formed by adding impurity of:
1. Phosphorous
2. Arsenic
3. Boron
4. Aluminum
Which of the above are correct ?
A
1 and 2
B
2 and 3
C
3 and 4
D
1 and 4
Question 4Single Answer
According to Einstein’s relationship for a semiconductor, the ratio of diffusion constant to the mobility of the charge carriers is
A
Variable and is twice the volt equivalent of the temperature
B
Constant and is equal to the volt equivalent of the temperature
C
Equal to two and is twice the volt equivalent of the temperature
D
Equal to one and is equal to the volt equivalent of the temperature
Question 5Single Answer
Swept-out voltage in PIN diode happens when PIN diode is
A
Forward biased and the thickness of the depletion layer decreases till I-region becomes free of mobile carriers
B
Reverse biased and the thickness of the depletion layer increases till I-region becomes free of mobile carriers
C
Forward biased and the thickness of the depletion layer increases till I-region becomes free of mobile carriers
D
Reverse biased and the thickness of the depletion layer decreases till I-region becomes free of mobile carriers
Question 6Single Answer
The number of holes in an N-type silicon with intrinsic value 1.5 × 1010/cm3 and doping concentration of 1017/cm3, by using mass-action law is
A
6.67 × 106/cc
B
4.44 × 10-25/cc
C
1.5× 10-24/cc
D
2.25 × 103/cc
Question 7Single Answer
A tunnel-diode is best suited for
A
Very low frequencies
B
50 Hz
C
100 Hz
D
Microwave frequencies
Question 8Single Answer
Small recovery time of a diode is most significant for
A
Line-frequency rectification
B
Switching operations
C
High-frequency rectifications and switching operations
D
Low-frequency rectifications and switching operations
Question 9Single Answer
In JFET, when operated above the pinch-off voltage, the
A
Depletion region becomes smaller
B
Drain current starts decreasing
C
Drain current remains practically constant
D
Drain current increases steeply
Question 10Single Answer
Thermal runaway is not possible in FET because, as the temperature of FET increases
A
The drain current increases
B
The mobility of charge carriers decreases
C
The mobility of charge carriers increases
D
The transconductance increases
Question 11Single Answer
Consider the following statements regarding an N-P-N Bipolar Junction Transistor:
1. Emitter diode is forward biased and collector diode is reverse biased
2. Emitter has many free electrons
3. Free electrons are injected into base and pass through collector
4. Depletion layers around junction J1 and J2 of BJT are widened
Which of the above statements are correct?
A
1, 2 and 4
B
1, 3 and 4
C
2, 3 and 4
D
1, 2 and 3
Question 12Single Answer
A freewheeling diode T phase controlled rectifier
A
Improves the line power factor
B
Enables inverse operation
C
Is responsible for additional reactive power
D
Is responsible for additional harmonics
Question 13Single Answer
The zeners incorporated within the encapsulations of some MOSFETs are meant for
A
Reducing the cost
B
Biasing the gate circuit
C
Self-protecting the device against transients
D
None of the above
Question 14Single Answer
When UJT is used for triggering an SCR, the wave-shape of the signal obtained from UJT circuit is
A
Sine wave
B
Saw tooth wave
C
Trapezoidal wave
D
Square wave
Question 15Single Answer
Darlington pairs are frequently used in linear ICs because, they
A
Do not require any capacitors or inductors
B
Have enormous impedance transformation capability
C
Can be readily formed/hooked from two adjacent transistors
D
Resemble emitter follower
Question 16Single Answer
In a MOS capacitance fabricate on a P-type semiconductor, strong inversion occurs, when potential is
A
Equal to Fermi level
B
Zero
C
Negative and equal to Fermi potential in magnitude
D
Positive and equal to Fermi potential in magnitude
Question 17Single Answer
A CMOS amplifier when compared to an N channel MOSFET has the advantage of
A
Higher cutoff frequency
B
Higher voltage gain
C
Higher current gain
D
Lower power dissipation
Question 18Single Answer
Consider the following statements regardingoptocouplers:
1. Optocouplers are LEDs driving photodiodes in a single package to provide electrical isolation between input and output
2. Optocouplers is LED driving a phototransistor in a single package that replaces pulse transformers working at input zero crossing
3. Optocouplers are used as temporary non fixed joints between optical fibre terminations
Which of the above statements are correct?
A
1, 2 and 3
B
1 and 2 only
C
1 and 3 only
D
2 and 3 only
Question 19Single Answer
Which of the following does not cause permanent damage to an SCR ?
A
High current
B
High rate of rise of current
C
High temperature rise
D
High rate of rise of voltage
Question 20Single Answer
The basic structure of an avalanche photodiode is
A
p+ – i – p – n+
B
p+ – I – n+
C
p+ – p- – n+
D
i – p- – n+
Question 21Single Answer
A five digits number is formed using the digits 1, 3, 5, 7 and 9 without repeating any of them. What is the sum of all such possible five digit numbers ?
A
6666660
B
6666600
C
6666666
D
6666606
Question 22Single Answer
Examples of an active display and a passive display respectively are
A
LCD and Gas discharge plasma
B
LED and LCD
C
Gas discharge plasma and LED
D
Electrophoretic Image display and LED
Question 23Single Answer
The dc resistivity and permeability exhibited by a type 1 superconductor are respectively
A
Zero and zero
B
Zero and unity
C
Unity and zero
D
Unity and unity
Question 24Single Answer
Statement (I):One of the mechanisms by which a transistor’s usefulness may be terminated, as the collector voltage is increased, is called punch through. Statement (II): Punch through results from the increased width of the collector-junction transition region with increased collector-junction voltage
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 25Single Answer
Statement (I): Conduction takes place in an enhancement MOSFET only for gate voltages below the threshold level. Statement (II):In an enhancement MOSFET, a channel of semiconductor of the same type as the source and drain is induced in the substrate by a positive voltage applied to the gate.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 26Single Answer
Statement (I): MOSFET is a field effect transistor whose drain current is controlled by the voltage applied at the gate. Statement (II): MOSFET is an insulated gate FET
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 27Single Answer
Statement (I): All passive components can be fabricated in a single chip. Statement (II): As opposed to discrete circuits where all components are separately inserted and connected, in an integrated circuit, they are simultaneously created on a chip of semiconductor material during manufacturing
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 28Single Answer
What is an advantage of MOS transistor structure in integrated circuits?
A
Faster switching
B
Less capacitance
C
Higher component density and lower cost
D
Lower resistance
Question 29Single Answer
An LTI system has a wide-sense stationary (WSS) input signal with zero mean. Its output is
A
Non-zero mean and non-WSS signal
B
Zero mean and WSS signal
C
Non-zero mean and WSS signal
D
Zero mean and non-WSS signal
Question 30Single Answer
In degenerately doped n conduction n-type semiconductor, the Fermi level lies in conduction band when
A
Concentration of electrons in the conduction band exceeds the density of states in the valence band
B
Concentration of electrons in the valence band exceeds the density of states in the conduction band
C
Concentration of electrons in the conduction band exceeds the product of the density of states in the valence band and conduction band
D
None of the above
Question 31Single Answer
The purpose of connecting a Zener diode in a UJT circuit, used for triggering thyristors, is to
A
Expedite the generation of triggering pulses
B
Delay the generation of triggering pulses
C
Provide a constant voltage to UJT to prevent erratic firing
D
Provide a variable voltage to UJT as the source voltage changes
Question 32Single Answer
Statement (I):With a small additional energy, usually thermal, the valence electrons in germanium can become free electrons. Statement (II):The valence electrons in germanium are in the fourth orbit and are at high energy level.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 33Single Answer
Statement (I): An FET is a current-controlled device. Statement (II): Operation of an FET depends only on majority.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 34Single Answer
Statement (I): Thermal runaway is not possible in an FET. Statement (II): As the temperature of an FET increases, the mobility of carriers decreases.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 35Single Answer
Statement (I): In an enhancement type MOSFET (with n-type source and drain regions), only positive voltage can be applied to the gate with respect to the substrate (p-type). Statement (II): Only with a positive voltage to the gate, an ‘inversion layer’ is formed and conduction can take place
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 36Single Answer
For a fully transposed transmission line
A
positive negative and zero sequence impedances are equal
B
positive and negative sequence impedances are equal
C
zero and positive sequence impedances are equal
D
negative and zero sequence impedances are equal
Question 37Single Answer
The best device for improving the switching speeds of bipolar transistors is
A
Speed-up capacitor
B
Transistor with higher cut-off frequency
C
Clamping diode
D
Clamping diode with zero storage time
Question 38Single Answer
The early effect in bipolar junction transistor is caused by
A
Fast turn-off
B
Fast turn-on
C
Large emitter to base forward bias
D
Large collector to base reverse bias
Question 39Single Answer
To get higher cut-off frequency in a BJT, base sheet resistance should be
A
Low
B
High
C
Equal to cut-off frequency
D
Zero
Question 40Single Answer
A BJT operates as a switch
A
In the active region of transfer characteristics
B
With no signal condition
C
Under small signal conditions
D
Under large signal conditions
Question 41Single Answer
What is the biasing condition of junctions in bipolar junction transistor to work as an amplifier?
A
Reverse biased base to emitter junction and reverse biased base to collector junction
B
Forward biased base to emitter junction and reverse biased base to collector junction
C
Forward biased base to emitter junction and forward biased base to collector junction
D
Reverse biased base to emitter junction and forward biased base to collector junction
Question 42Single Answer
In a JFET, operating above pinch-off voltage, the
A
Drain current increases steeply
B
Drain current remains practically constant
C
Drain current starts decreasing
D
Depletion region reduces
Question 43Single Answer
If Vcc = 18V, voltage divider resistances R1 = 4.7 kΩ and R2 = 1500 Ω, what is the base bias voltage?
A
8.70 V
B
4.35 V
C
2.90 V
D
0.70 V
Question 44Single Answer
An SCR has an anode supply of sine voltage 200Vr.m.s., 50 Hz applied through a 100 Ω resistor and fired at an angle of 60°. Assuming no voltage drop, the r.m.s. value of the output voltage is nearly
A
90 V
B
126 V
C
166 V
D
200 V
Question 45Single Answer
In a GTO, anode current begins to fall when gate current
A
Is negative peak at time t=0
B
Is negative peak at time t=storage period
C
Just begins to become negative at t=0
D
Just begins to become positive at t=0
Question 46Single Answer
An SCR is turned off when its turn-off time is
A
less than the circuit time constant
B
greater than the circuit time constant
C
less than the circuit turn-off timex
D
greater than the circuit turn-off time
Question 47Single Answer
The bandwidth of a digitally recorded signal primarily depends upon
A
The physical properties of the system components processing the signal
B
The frequency at which the signal is sampled
C
The frequency of the clock signal that is used to encode binary values responding the signal
D
The frequency of the noise affecting signal quality
Question 48Single Answer
While measuring the voltage developed by a thermocouple, it is found that there is always an offset voltage. This is due to
A
A voltage across thermocouple even at very low temperature
B
Some photoelectric voltage across the junction due to ambient light
C
A barrier potential across the junction
D
An additional thermocouple is formed due to the connecting wires and one of the metals.
Question 49Single Answer
For an antenna, radiation intensity is defined as
A
The time-averaged radiated power per unit solid angle
B
The peak radiated power per unit solid angle
C
The peak radiated power per unit area
D
The time-averaged radiated power per unit area
Question 50Single Answer
A source of (power/energy) feeds the input port of an amplifier and the output port is connected to a ‘load’. The input impedance of the ideal amplifier should ideally be
A
Zero
B
∞
C
Low
D
high
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Electronics
Question 51Single Answer
Medium doping in Silicon and Germanium corresponds to impurity of the order of
A
1 part in 106
B
1 part in 105
C
1 part in 104
D
1 part in 108
Question 52Single Answer
An electric field is applied to a semiconductor. Let the number of charge carriers be n and the average drift speed by v. If the temperature is increased then
A
Both n and v will increase
B
n will increase but v will decrease
C
v will increase but n will decrease
D
Both n and v will decrease
Question 53Single Answer
Statement (I): Centre tap transformer is essential for a centre-tapped rectifier. Statement (II): In half wave rectification minimum two diodes are required.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 54Single Answer
Statement (I): Power factor is a measure of the power flow in the insulator and should be low. Statement (II): It varies with the temperature and usually increases with the rise in temperature of the insulation.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 55Single Answer
Statement (I): An SCR has a current controlled negative resistance characteristic. Statement (II):For a given current the voltage can be determined while for a given voltage current cannot be determined.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 56Single Answer
Statement (I): JEET is operated in depletion mode only. Statement (II): The input resistance of a MOSFET is several orders of magnitude greater than that of a JEET.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 57Single Answer
Statement (I): A photodiode is an example of a photo-conductive sensor. Statement (II): A photodiode can be used as either a photo conductive or a photo resistive sensor.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 58Single Answer
A heavily doped semiconductor has
A
A resistivity which decreases exponentially with temperature
B
A resistivity which rises almost linearly with temperature
C
A negative temperature coefficient of resistance
D
A positive temperature coefficient of resistance
Question 59Single Answer
A Zener diode has the following properties:
1. It is properly doped crystal diode with sharp breakdown.
2. It is reverse biased
3. Its forward characteristics are just that of ordinary diode
4. Its reverse characteristics are like and ordinary diode
A
1, 2, 3 and 4
B
1, 2 and 4 only
C
1, 2 and 3 only
D
3 and 4 only
Question 60Single Answer
A tunnel diode is a p-n junction in which
A
n-region is degenerately doped
B
p-region is degenerately doped
C
either n or p-region is degenerately doped
D
both n and p-regions are degenerately doped
Question 61Single Answer
Which is the diode used for measuring light intensity?
A
Junction diode
B
Varactor diode
C
Tunnel diode
D
Photo diode
Question 62Single Answer
Which of the following are essentials of a transistor biasing circuit?
1. Proper zero signal collector current flow
2. VCE should not fall below 0.5 V for Germanium and 1 V for Silicon
3. Ensure stabilization of operating point
4. Loading to the source
A
1, 2 and 3 only
B
1, 2 and 4 only
C
3 and 4 only
D
1, 2, 3 and 4
Question 63Single Answer
Which of the following options is the closet meaning to the sentence given below?
A
she had a terrible time at the party
B
she had a horrible time at the party
C
she had a terrific time at the party.
D
she had a terrifying time at the party
Question 64Single Answer
When a transistor is saturated,
A
The emitter potential is more than the base-collector potential
B
The collector potential is more than the base-emitter potential
C
The base potential is more than the emitter-collector potential
D
The base, emitter and collector are almost the same potential
Question 65Single Answer
If the value of a transistor changes 0.5% from its nominal value of 0.9, the percentage change in b will be
A
0%
B
2.5%
C
5%
D
7.5%
Question 66Single Answer
If an npn silicon transistor is operated at VCE = 5 V and IC = 100 and has a current gain of 100 in the CE connection, then the input resistance of this circuit will be
A
250 Ω
B
25 kΩ
C
250 kΩ
D
2500 kΩ
Question 67Single Answer
In a bipolar junction transistor an increase in magnitude of collector voltage increases the space-charge width at the output junction diode. This causes the effective base width to decrease. This effect is known as
A
Hall effect
B
Early effect
C
Miller effect
D
Zener effect
Question 68Single Answer
Given set A ={2, 3, 4, 5} set B = {11, 12, 13, 14, 15}, two numbers are randomly selected one form each set. What is the probability if the sum of the two numbers is equals to 16?
A
0.20
B
0.25
C
0.30
D
0.33
Question 69Single Answer
Most of the linear ICs are based on two-transistor differential amplifiers because of
A
Input voltage-dependent linear transfer characteristic
B
High voltage gain
C
High input resistance
D
High CMRR
Question 70Single Answer
When the photo resist coating (during IC fabrication) is exposed to ultraviolet light the photo resist becomes
A
Oxidized
B
Ionized
C
Polymerized
D
Brittle
Question 71Single Answer
The concentration of hole-electron pairs in pure silicon at T = 300 K is 7 × 1015 per cubic metre. Antimony is doped into silicon in a proportion of 1 atom in 107 atoms. Assuming that half of the impurity atoms contribute electrons in the conduction band, the factor by which the number of charge carriers increase due to doping (the number of silicon atoms per cubic metre is 5 × 1028 ) is
A
14 × 1015
B
0.5 × 1021
C
2.5 × 1021
D
1.8 × 105
Question 72Single Answer
A potential barrier of 0.50 V exists across a p-n junction. If the depletion region is 5.0 × 107 m wide, what is the intensity of the electric field in this region?
A
1.0 × 106 V/m
B
2.5 × 10-7 V/m
C
2.5 × 107 V/m
D
2.5 × 108 V/m
Question 73Single Answer
In a trans conductance, the device output
A
Voltage depends upon the input voltage
B
Voltage depends upon the input current
C
Current depends upon the input voltage
D
Current depends upon the input current
Question 74Single Answer
if the drift velocity of holes under a field gradient of 200 V/m is 100m/s, their mobility in SI units is
A
0.5
B
0.05
C
50
D
500
Question 75Single Answer
The given statement is followed by some course of action. Assuming the statement to be true, decide the correct option.
There has been a significant drop in the water level in the lakes supplying water to the city
Courses of action
I. the water supply authority should impose a partial cut in supply to tackle the situation
II. the government should appeal to all the residents through mass media for minimal use of water.
III. the government should ban the water supply in lower areas.
A
statement I and II follow.
B
statement I and III follow.
C
statement II and III follow.
D
all statement follow.
Question 76Single Answer
Hall effect is useful for the measurement of a semiconductor’s
A
Mobility, carrier concentration and temperature
B
Type (n-type or p-type), conductivity and temperature
C
Type (n-type or p-type), mobility and carrier concentration
D
Mobility, conductivity and temperature
Question 77Single Answer
A freewheeling diode in a phase-controlled rectifier
A
Improves the line power factor
B
Is responsible for additional reactive power
C
Prevents inverse operation
D
Is responsible for additional harmonics
Question 78Single Answer
The relative values of the forward conduction voltage for a p-njunction diode, a Red LED and a Schottky barrier diode are
A
Schottky voltage drop >p-njunction diode drop > Red LED drop
B
Red LED drop >p-njunction diode drop >Schottky voltage drop
C
p-njunction diode drop >Schottky voltage drop > Red LED drop
D
Schottky voltage drop > Red LED drop >p-njunction diode drop
Question 79Single Answer
The number of students in a class who have answered correctly, wrongly, or not attempted each question in an exam, are listed in the table given below. The marks for each question are also listed. There is no negative or partial marking. What is the average of the marks obtained by the class in the examination?
A
2.290
B
2.970
C
6.795
D
8.795
Question 80Single Answer
The I-V characteristics of a tunnel diode exhibit?
A
Current-controlled negative resistance
B
Voltage-controlled negative resistance
C
Temperature-controlled positive resistance
D
Current-controlled positive resistance
Question 81Single Answer
A gate to drain-connected enhancement mode MOSFET is an example ofx
A
An active load
B
A switching device
C
A three-terminal device
D
A diode
Question 82Single Answer
Thermal runaway is not possible in FET because, at the temperature of FET increases
A
The drain current increases
B
The mobility increases
C
The mobility decreases
D
The transconductance increases
Question 83Single Answer
The output impedance of a BJT under common-collector configuration is
A
Low
B
High
C
Medium
D
Very high
Question 84Single Answer
Consider the following statements related to JFET:
1.Its operation depends on the flow of minority carriers only
2.It is less noisy than BJT
3.It has poor thermal stability
4.It is relatively immune to radiation
The correct statements are
A
1, 2, 3 and 4
B
1 and 2 only
C
2 and 4 only
D
3 and 4 only
Question 85Single Answer
Shunt reactors are sometimes used in high voltage transmission system to
A
limit the short circuit current through the line
B
compensate for the series reactance of the line under heavily loaded condition
C
limit over voltage at the load side under lightly loaded condition
D
compensate for the voltage drop in the line under heavily loaded condition
Question 86Single Answer
The radius of the first Bohr orbit of electrons in hydrogen atom is 0.529 Å. What is the radius of the second Bohr orbit in singly ionized helium atom?
A
1.058 Å
B
0.264 Å
C
10.58 Å
D
0.0264 Å
Question 87Single Answer
For which one of the following materials, is the Hall coefficient closest to zero?
A
Metal
B
Insulator
C
Intrinsic semiconductor
D
Alloy
Question 88Single Answer
A 3-phase, 4-pole, self excited induction generator is feeding power to a load at a frequency f1. If the load is partially removed the frequency becomes f2. If the speed of the generator is maintained at 1500 rpm in both the cases, then
A
f1f2 > 50HZ and f1 > f2
B
f1 < 50HZ and f2 > 50HZ
C
f1f2 < 50HZ and f2 > f1
D
f1 > 50HZ and f2 < 50HZ
Question 89Single Answer
The energy gap in the energy band structure of a material is 9 eV at room temperature. The material is
A
Semiconductor
B
Conductor
C
metal
D
Insulator
Question 90Single Answer
Consider the following statements related to piezoelectric effect:
1.It gives electrical response in terms of voltage change when mechanical stress occurs in some materials
2.It gives mechanical response in terms of dimensional change due to electrical excitation of some materials
Which of the above statements is/are correct?
A
1 only
B
2 only
C
Neither 1 nor 2
D
Both 1 and 2
Question 91Single Answer
Which of the following materials has temperature coefficient of resistivity very close to zero?
A
Manganin
B
Nichrome
C
Carbon
D
Aluminum
Question 92Single Answer
Consider an LTI system with impulse response h(t) = e-5t u(t). if the output of the system is y(t) = e-3t u(t) –e -5t u(t), then the input x(t), is given by
A
e-3tu(t)
B
2 e-3tu(t)
C
e-5tu(t)
D
2e-5tu(t)
Question 93Single Answer
In a thyristor, the minimum current required to maintain the device in the ‘ON’ state is called
A
Latching current
B
Ignition current
C
Holding current
D
Avalanche current
Question 94Single Answer
Which of the following magnetic materials has the highest reluctance?
A
Ferromagnetic
B
Paramagnetic
C
Diamagnetic
D
None of the above
Question 95Single Answer
The cut-off frequency of a rectangular waveguide in dominant mode is 10GHz. The width of the wave guide is
A
2 cm
B
1.5 cm
C
1 cm
D
2.5 cm
Question 96Single Answer
Which one of the following plays and important role in the fine recording of audio signals on magnetic tape recorder?
A
Width of the air gap of the recording head
B
Thickness of the tape used for recording
C
Material of the recording head
D
Speed of the motor
Question 97Single Answer
A resistance strain gauge with a gauge factor of 3 is fixed to a steel member subjected to a stress of 100 N/m. The Young’s modulus of steel is 2 × 105 N/mm2.The percentage change in resistance is
A
0.1%
B
0.15%
C
1.0%
D
1.5%
Question 98Single Answer
In eddy current damping system, the disc employed should be of
A
Conducting and magnetic material
B
Conducting but non-magnetic material
C
Magnetic but non-conducting material
D
non-conducting and non-magnetic material
Question 99Single Answer
Which one of the following thermocouple pairs has maximum sensitivity around 273K?
A
Nichrome-constantan
B
Copper-Nickel
C
Platinum-constantan
D
Nickel-constantan
Question 100Single Answer
Statement (I):In ferroelectric materials, domains with permanent electric dipoles may be created that would align along external electric field. Statement (II):Ferroelectric materials undergo phase transformation of symmetric to asymmetric structure below a critical temperature.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 101Single Answer
Statement (I): Ferrite cored coils are used in high frequency tuned circuits Statement (II): Ferrite cored coils have high Q as compared to iron-cored coils. formation of symmetric to asymmetric structure below a critical temperature.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 102Single Answer
The atomic packing factor for face-centered cubic (FCC) crystal structure is
A
0.63
B
0.74
C
7.4
D
6.3
Question 103Single Answer
Drift velocity in a metal is
A
Inversely proportional to the force on an electron due to applied electric field
B
Directly proportional to the mass of an electron
C
Proportional to the mobility of an electron
D
Inversely proportional to the strength of the applied electric field
Question 104Single Answer
The three kinds of breakdowns possible in solid dielectrics are electrothermal, purely electrical and
A
Electromechanical
B
Purely thermal
C
Electrochemical
D
Spontaneous
Question 105Single Answer
For a particular material, the Hall coefficient is found to be zero. The material is
A
Intrinsic semiconductor
B
Extrinsic semiconductorx
C
Metal
D
Insulator
Question 106Single Answer
A 12V automobile light is rated at 30 W. The total charge that flows through the filament in one minute is
A
30 C
B
12 C
C
150 C
D
180 C
Question 107Single Answer
At very high temperature, an n-type semiconductor behaves like
A
A p-type semiconductor
B
An intrinsic semiconductor
C
A superconductor
D
An n-type semiconductor
Question 108Single Answer
The Fermi level in a p-type semiconductor lies close to
A
Top of the valence band
B
Bottom of the valence band
C
Top of the conduction band
D
bottom of the conduction band
Question 109Single Answer
Covalent bond energy in germanium is about
A
7.4 eV
B
31 eV
C
3.4 eV
D
20.4 eV
Question 110Single Answer
The relationship between relative permeability and magnetic susceptibility of the medium is
A
B
C
D
Question 111Single Answer
Ferromagnetic property may be explained on the basis of
A
Faraday’s theory
B
Curie-Weiss theory
C
Domain theory
D
Einstein’s theory
Question 112Single Answer
Soft iron is characterized by the saturation magnetization MS, coercivity HC and retentivity BC. It is suitable for an electromagnet because
A
MS, HCand BCare small
B
MSis small, HCand BCare large
C
MSis large, HCand BCare small
D
MS , HC and BC are large
Question 113Single Answer
Diamagnetic susceptibility is very
A
Small and negative
B
Small and positive
C
Large and negative
D
Large and positive
Question 114Single Answer
Magnetostriction is the effect produced when change of magnetization is magnetic material results in
A
Change of permeability
B
Change in dimensions
C
Change of temperature
D
Change of magnetic field strength
Question 115Single Answer
Commonly used dielectric, in electrolytic capacitors is
A
Magnesium oxide
B
Cadmium nitride
C
Aluminum
D
Manganese oxide
Question 116Single Answer
The electrical conductivity and electron mobility for aluminum are 3.8 × 107 (ohm-m)-1 and 0.0012 m2/V-s, respectively. What is the Hall voltage for an aluminum specimen that is 15 mm thick for a current of 25A and a magnetic field of 0.6 tesla (imposed in a direction perpendicular to the current) for the given value of Hall coefficient, RH as –3.16 × 10-11 V-m/A-tesla?
A
–316 × 10-8 V
B
–3.16 × 10-8 V
C
316 × 10-8 V
D
3.16 × 10-8 V
Question 117Single Answer
Absolute encoders, are normally used for
A
One revolution
B
Continuous speed in clockwise direction
C
Continuous speed in counter clockwise direction
D
Counting least significant bits
Question 118Single Answer
1. A very good HF response
2. Typical output voltage of the order of 1mV to 30 mV per unit of acceleration
3. No requirement of external power and is self-generating
4. No response for static conditions
Which of the above statements are correct?
A
1, 2 and 3 only
B
1, 2 and 4 only
C
3 and 4 only
D
1, 2, 3 and 4
Question 119Single Answer
A piezoelectric crystal having a thickness of 2 mm and a voltage sensitivity of 0.02 V-m/N is subjected to a pressure of 20 × 103 Pa. What is the output voltage?
A
0.775 V
B
0.80 V
C
0.002 × 10-6 V
D
0.2 × 10-6 V
Question 120Single Answer
Cold junction in a thermocouple is
A
The reference junction maintained at a known constant temperature
B
The junction maintained at a very low temperature
C
The junction at which the temperature is sensed
D
None of the above
Question 121Single Answer
Statement (I): Hard magnetic materials are used for making permanent magnets. Statement (II): Hard magnetic materials have relatively small and narrow hysteresis loop
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is not the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 122Single Answer
The basic material for fabrication of an LED is
A
Gallium arsenide
B
Gallium arsenide phosphide
C
Indium antimonide
D
Indium antimonide phosphide
Question 123Single Answer
n-p-ntransistors are preferred over p-n-p transistors because they have
A
High mobility of holes
B
High mobility of electrons
C
low mobility of holes
D
higher mobility of electrons than the mobility of holes in p-n-p transistors
Question 124Single Answer
A p-type silicon sample has an intrinsic carrier concentration of 1.5 × 1010 /cm3and a hole concentration of 2.25 × 1015 /cm3. Then the electron concentration is
A
1.5 × 1025 /cm3
B
105 /cm3
C
1010/cm3
D
0
Question 125Single Answer
The strain gauge should have
1.High gauge factor
2.Low resistance temperature coefficient
3.High resistance
Which of the above statements are correct?
A
1 and 2 only
B
1 and 3 only
C
2 and 3 only
D
1, 2 and 3
Question 126Single Answer
A resistance strain gauge with gauge factor of 3 is subjected to a stress of 3000kg/cm when fastened to a steel rod. The modulus of elasticity of steel is 2.1× 106 kg/cm2. The percentage change in resistance of the strain gauge element is
A
0.1428%
B
24.84%
C
0.4284%
D
4.3%
Question 127Single Answer
In a semiconductor strain gauge, the change in resistance on application of strain is mainly due to change in
A
Length of the wire
B
Diameter of the wire
C
Resistivity of the material of the wire
D
Both the length and diameter of the wire
Question 128Single Answer
The coordination number and the atomic packing factor for Hexagonal Closed Packed (HCP) and Face Centered Cubic crystal structure are respectively
A
8 and 0.74
B
12 and 0.68
C
8 and 0.68
D
12 and 0.74
Question 129Single Answer
The resistivity of material is a function of temperature because
A
Election density varies with temperature
B
Election gas density varies with temperature
C
Amplitude of vibration of atom varies with temperature
D
All of the above
Question 130Single Answer
In a piezoelectric crystal oscillator, if x represents the mass of the crystal, then the oscillation or tuning frequency is linearly proportional to
A
Mass of the crystal
B
The square root of the mass of the crystal
C
The square of the mass of the crystal
D
The inverse of the square root of the mass of the crystal
Question 131Single Answer
The temperature above which an antiferromagnetic material becomes paramagnetic is called
A
Neel temperature
B
Peak temperature
C
Critical temperature
D
Weiss temperature
Question 132Single Answer
The relative permeability is less than 1 in
A
Ferromagnetic materials
B
Diamagnetic materials
C
Paramagnetic materials
D
Ferrites
Question 133Single Answer
Which one of the following quantities can be measured with the help of piezoelectric crystal?
A
Acceleration
B
Flow
C
Temperature
D
Velocity
Question 134Single Answer
As per Curie-Weiss law, the magnetic susceptibility of a material varies as
A
T-2
B
1/T
C
T
D
T2
Question 135Single Answer
Ferrites have
A
Low copper
B
Low eddy current loss
C
Low resistivity
D
Higher specific gravity than that of the iron
Question 136Single Answer
Statement (I): Aliasing occurs when the sampling frequency is less than twice the maximum frequency in the signal. Statement (II):Aliasing is a reversible process.
A
Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)
B
Both Statement (I) and Statement (II) are individually true and Statement (II) is NOT the correct explanation of Statement (I)
C
Statement (I) is true but Statement (II) is false
D
Statement (I) is false but Statement (II) is true
Question 137Single Answer
For a sheet with resistivity , width length , and thickness the resistance per square (sheet resistance) RS is
A
B
C
D
Question 138Single Answer
An optical fibre has refractive index core
A
High and low refractive index cladding
B
low and high refractive index cladding
C
uniform surrounded by variable index cladding
D
Variable with refractive index increases from low at the center to high at the junction with cladding
Question 139Single Answer
The wavelength beyond which photo-electric emission cannot take place is called
A
Long wavelength
B
Optical wavelength
C
Photoelectric wavelength
D
Critical wavelength
Question 140Single Answer
Match List-I and List-II List-I List-II
A. Electrostriction 1. Converse of Seeback effect
B. Ionic conductivity 2. Reverse effect of piezoelectricity
C. Peltier heat 3. Converse effect of magnetostriction
D. Villari effect 4. Conductivity of insulators
A
A B C D
2 4 1 3
B
A B C D 3 4 1 2
C
A B C D 2 1 4 3
D
A B C D 3 1 4 2
Question 141Single Answer
A piece of writing paper that is 10 cm wide, 15 cm long and 0.05 mm thick gas a dielectric strength of 8 kV/mm. If it is placed between two copper plates and subjected to an increasing voltage, it will bread down at
A
8 kV
B
4 kV
C
0.4 kV
D
0.8 kV
Question 142Single Answer
Superconductors are becoming popular for their use in
A
Generating very strong magnetic field
B
Manufacture of bubble memories
C
Generating electrostatic field
D
Generating regions free from magnetic field
Question 143Single Answer
Match List-I and List-II List-I List-II
A. di/dt rating limits 1. Snubber circuit
B. dv/dt rating limits 2. Heat sink
C. i2t limit 3. Series reactor
D. Junction temperature limit 4. Fuse
Codes
A
A B C D
2 4 1 3
B
3 4 1 2
C
2 1 4 3
D
3 1 4 2
Question 144Single Answer
Two coils N1 and N2 turns are wound concentrically on a straight cylindrical core of radius and permeability. The windings have length l1 and l2 respectively as shown in figure. The mutual inductance will be
1 Proportional to N1N2
2 Proportional to
3 Inversely Proportional to l1
4Inversely Proportional to r2
Which of these statements are correct?
A
1, 2, 3 and 4
B
2, 3 and 4
C
1, 2 and 3
D
1, 3 and 4
Question 145Single Answer
A varying magnetic flux linking a coil is given by the emf induced is 9 V, then the value of is
A
Zero
B
1 Wb/s2
C
-1 Wb/s2
D
9 Wb/s2
Question 146Single Answer
If the potential, V= 4x +2 volts, the electric field is
A
6 V/m
B
2 V/m
C
4 V/mx
D
Question 147Single Answer
If the current element represented by Amp-m is placed in a magnetic field of the force on the current element is
A
B
C
D
Question 148Single Answer
Match List-I and List-II List-I List-II
A MMF 1. Conductivity
B Magnetic flux 2. Electric current
C Reluctance 3. EMF
D Permeability 4. Resistance
Codes
A
A B C D
3 4 2 1
B
1 2 4 3
C
3 2 4 1
D
1 4 2 3
Question 149Single Answer
Match List-I and List-II
List-I List-II
A Ferrite 1. Meissner effect
B Superconductor 2. Farady effect
C Quartz 3. Hysteresis
D Iron 4. Piezoelectricity
Codes
and magnetic susceptibility 
of the medium is
, width 
length 
, and thickness 
the resistance per square (sheet resistance) RS is
the emf induced is 9 V, then the value of is
Amp-m is placed in a magnetic field of 
the force on the current element is
