Lecturer in Electronics Engineering - Technical Education 318/2015 Answer Key

Post : Lecturer in Electronics Engineering
Department : Technical Education
Category Code : 318/2015
Question Paper Code : 52/2017/OL
Date of Test : 04-07-2017

The minority carrier current in a semiconductor diode is largely a function of
- Amount of doping
- Temperature
- Forward bias voltage
- Reverse bias voltage
When the transistor is in high saturation, the biasing condition of base emitter BE and collector base CB junction is
- BE forward biased, CE reverse biased
- BE reversed biased, CE forward biased
- BE forward biased, CE forward biased
- BE reverse biased, CE reverse biased
Memory that loses its contents when power is lost is
- Non volatile
- Volatile
- Flash memory
- Static memory
In a bridge rectifier, if Vm is the peak voltage across the secondary of transformer, the maximum voltage coming across each reverse biased diode is
- Vm/2
- Vm/√2
- 2Vm
- Vm
The main advantage of CMOS is its
- Low power consumption
- High power rating
- Small signal operation
- Fast switching capability
The space-charge region contains charges that are
- Mostly majority carriers
- Mostly minority carriers
- Fixed donor and acceptor ions
- Mobile donor and acceptor ions
The microwave tube that uses buncher and catcher cavities is
- Magnetron
- Klystron
- Reflex Klystron
- Traveling wave tube
Which of the following has same probability of error?
- BPSK and QAM
- BPSK and ASK
- BPSK and QPSK
- BPSK and PAM
The negative resistance of the tunnel diode occurs when the bias voltage is
- Between the peak and valley voltages
- Above the valley voltage
- Below the peak voltage
- In the reverse direction
In an RC differentiator, the condition for differentiation is
- RC >> 0.16T
- RC << 0.16T
- RC >> T/0.16
- RC << T/0.16
For an input pulse train of clock period T, the delay produced by an n stage shift register is
- 2nT
- nT
- (n + 1)T
- (n - 1)T
An n-channel JFET has I(DSS) = 1 mA and V(P) = -5 V. Its maximum transconductance is
- 0.4 millimho
- 0.1 millimho
- 1.0 millimho
- 4.0 millimho
For thyristors, pulse triggering is preferred to dc triggering because
- Gate dissipation is low
- Pulse system is simpler
- Triggering system is required for a very short duration
- All of these
If an amplifier with a gain of −1000 and feedback of β=−0.1 had a gain change of 20% due to temperature, the change in gain of the feedback amplifier would be
- 0.2%
- 5%
- 10%
- 0.01%
The sensitivity of a multimeter is given in
- Ω
- KΩ/V
- Amperes
- V/KΩ
A superheterodyne radio receiver with an intermediate frequency of 455 KHz is tuned to a station operating at 1200 KHz. The associated image frequency is
- 55 KHz
- 1110 KHz
- 2110 KHz
- 4220 KHz
The multivibrator circuit configuration that can be used to convert a sinusoidal input into a square wave output is
- A stable multivibrator
- Monostable multivibrator
- Bistable multivibrator
- Schmitt trigger
A Yagi antenna in a horizontal plane produces
- A broadside pattern
- An endfire pattern
- A figure of eight pattern
- None of these
A problem with class B push pull amplifier is that they usually suffer from
- Harmonic distortion
- Intermodulation distortion
- Cross-over distortion
- None of these
A 12 bit binary number has an accuracy equivalent to the decimal fraction
- 1/1024
- 1/2048
- 1/6400
- 1/4096
If a pulse train with a frequency of 10 KHz is applied to the trigger input of a bistable multivibrator, the frequency of the output pulse train would be
- 5KHz
- 20 KHz
- 10 KHz
- None of these
Six independent low pass signals of bandwidth 3 W, W, W, 2W, 3W and 2W Hz are to be time division multiplexed on a common channel using PAM. To achieve this, the minimum transmission bandwidth of the channel should be __________ Hz.
- 12W
- 6W
- 3W
- 24W
Class a amplifiers are characterised by
- Maximum efficiency and minimum distortion
- Minimum efficiency and maximum distortion
- Maximum efficiency and maximum distortion
- Minimum efficiency and minimum distortion
From cricuit design simplicity and economy point of view, one of the following configurations for a converter is the best. Which is that?
- Push-pull DC-DC converter using one transformer
- Ringing choke converter
- Push-pull converter using two transformers
- None of these
An op-amp is having is having an open loop gain of `10^(5)` and open loop upper cutoff frequency of 10 Hz. If this op-amp is connected as an amplifier with a closed loop gain at 100, then the new upper cutoff frequency will be
- 10 Hz
- 100 Hz
- 10 KHz
- 100 KHz
An amplifier power level is changed from 8 Watts to 16 Watts, equivalent dB gains is
- 2 dB
- 3 dB
- 6 dB
- 5 dB
Which of the following statements are correct for the basic transistor amplifier configurations
- CB amplifier has low input impedance and a low current gain
- CC amplifier has low output impedance and a low current gain
- CE amplifier has very poor voltage gain but very high input impedance
- None of these
In antenna measurement using two aperture antennas of dimensions D1 and D2, minimum speparation between the two should be (λ is free space wavelength of radiation uses)
- (D1 + D2)/(2λ)
- (D1²+D2²) /(λ)
- (D1²+D2² /(8λ)
- (D1²+D2²) /2λ)
Compared to the junction transistor, FET//1) Has a larger gain bandwidth product//2) Is less noisy//3) Has less input resistance//4) Has only the majority carrier flow//The correct statements are
- 1, 3
- 1, 2
- 3, 4
- 2, 4
How does 80386 change operation from real mode to protected mode?
- By resetting MSB of CR1 contents
- By setting MSB of CR0 contents
- By setting MSB of CR1 contents
- By setting MSB of CR2 contents
A source follower (using a FET) usually has a voltage gain which is
- Slightly less than unity, but positive
- Greater than +1
- Exactly unity but negative
- About -10
Which of the following logic family consumes the least amount of power?
- I² L
- ECL
- TTL
- CMOS
In a 100% amplitude modulated signal, the power in the lower sideband is : Assume carrier power to be 100 watts and modulation system to be SSBSC.
- 50 watts
- 100 watts
- 25 watts
- None of these
A combinational logic circuit which is used to sen data coming from a source to two or more separate destinations is called as
- Demultiplexer
- Encoder
- Multiplier
- Decoder
The pinch off voltage of a JFET is 5V. Its cut off voltage is
- 5^1/2V
- 2.5 V
- 5^3/2V
- 5.0 V
A full wave rectifier uses two diodes, the internal resistance of each diode may be 20Ω each. The transformer rms secondary voltage from centre tap to each of secondary is 50V and load resistance is 980 Ω. Find the mean load current and rms value of load current.
- 0.05/√2 , 0.05π
- 0.05√2/π , 0.05
- 0.1√2/π ,0.05
- 50√2/π , 50
The 2732 is a 4096 x 8 EPROM. How many address lines does it have?
- 8
- 12
- 1600
- 2732
A lamp is controlled from two positions A and B (eg : staircase circuit). The boolean expression for the above circuit is
- AB+AB̅
- A̅B+AB̅
- AB+A̅B̅
- AB̅+A̅B̅
Most of the linear IC s are based on the two transistor differential amplifier because of its
- High CMRR
- High voltage gain
- High input resistance
- Input voltage dependent linear transfer characteristics
A speech signal occupying the bandwidth of 300 Hz to 3 KHz is converted into PCM format for use in digital communication. If the sampling frequency is 8 KHz and each sample quantized into 256 levels, then the output bit rate will be
- 3 Kb/s
- 8 Kb/s
- 256 Kb/s
- 64 Kb/s
A push pull inverter provides a
- Highly regulated output
- Constant DC output
- Square wave output
- None of these
When an antenna is placed in a vertical plane it will produce?
- Circularly polarised waves
- Elliptically polarised waves
- Horizontally polarised waves
- Vertically polarised waves
The octal equivalent of decimal 324.781 is
- 40.987
- 540.781
- 215.234
- 504.771
In a travelling wave tube, the phase velocity of the axial components of the field of the slow wave structure is kept
- Slightly less than the velocity of electrons
- Equal to the velocity of the electrons
- Slightly more than the velocity of electrons
- Equal to the velocity of light in free space
Address bus of 8086 contains
- 20 lines
- 32 lines
- 16 lines
- 24 lines
The propagation delay for ECL IC family is approximately
- 2ns
- 10ns
- 25ns
- 50ns
The pre-emphasis circuit is used
- After modulation
- To increase or emphasise the low amplitude frequency
- Prior to modulation
- None of these
A NAND circuit with positive logic will operate as
- AND with negative logic
- AND with negative logic
- OR with negative logic
- NOR with negative logic
The average on state current for an SCR is 20A for a conduction angle of 120°. The average on state current for 60° conduction angle will be
- 20 A
- Less than 20 A
- 10 A
- 40 A
A switched mode power supply operating at 20 KHz to 100 KHz range uses _______ as the main switching element.
- MOSFET
- Triac
- Thyristor
- UJT
The biggest disadvantage of CW Doppler radar is that
- It does not give the target position
- It does not give target velocity
- It does not give target range
- A transponder is required at the target
The field frequency of HDTV is
- 15
- 60
- 30
- 120
An NPN transistor has a beta frequency fβ of 1 MHz, and emitter short circuit low frequency current gain β(0) of 200. The unity gain frequency fT and alpha cutoff frequency fα respectively are
- 199 MHz, 200 MHz
- 200 MHz, 199 MHz
- 201 MHz, 200 MHz
- 200 MHz, 201 MHz
An opamp has a slew rate of 5V/μS. The largest sine wave output voltage possible at frequency of 1 MHZ is
- 10π volts
- 5 volts
- (5/π)volts
- (5/2π)volts
The number of comparisons carried out in a 5 bit flash type A/D converter is
- 31
- 32
- 5
- 3
A PLA can be used
- As a dynamic memory
- To realise a combinational logic
- As a microprocessor
- To realise a sequential logic
Hamming codes are used for error detection and correction. If the minimum hamming distance is m, then the number of errors correctable is
- Equal to 2 m
- Equal to m
- Less than m/2
- Greater than m
Given that W=e^(-i(2π/N) , where N = 3. Then F = W^N can be computed as F =
- 0
- 1
- e
- -1
The code division multiple access techniques is not used in satellite communication because of
- Wastage of power
- Wastage of baseband spectrum
- Increase in delay
- Complexity and unreliability of operation
Which of the following is introduced in the frequency sampling realization of the FIR filter?
- Poles are more in number on unit circle
- Zeros are more in number on the unit circle
- Poles and zeros at equally spaced points on the unit circle
- None of these
The number of LED display indicators in logic probes are
- 1
- 4
- 1 or 2
- 2
In a linear IC voltage, series pass transistor always operates in _________ region.
- Active
- Saturation
- Cutoff
- All of these
The data rate of QPSK is ________ of BPSK.
- Thirce
- 4 times
- Twice
- Same
Asymmetrical astable multivibrartor has R = 100Ω and C =0.1mF. The periodic time T is equal to
- 138 mS
- 69 mS
- 6.9 mS
- 13.8 mS
Bootstrap sweep circuit generally employs
- CE amplifier
- Emitter follower
- CB amplifier
- Tuned amplifier
If P=and Q= , then PQ is
- A null matrix
- An identity matrix
- A singular matrix
- A symmetric matrix
If P = , then P^-1=
The first three terms in the expansion of (a+bx)^m are 1, 6x and 16x² respectively (α > 0, m is a natural number). Then
- m = 9, b = 2/3
- m = 2, b = 3
- m = 4, b = 3/2
- m = 3, b = 2
The value of cot 1°+ cot 89° is
- 0
- 1
- 2/sin2°
- None of these
In Δ ABC, the value of is
- −2 tan A sin B cos C
- 0
- tan2A
- tan A(tan A−2 sin B cos C)
The x-intercept of the line passing through the point (1, 1) and perpendicular to the line x − 2y + 1 = 0 is
- 2/3
- -2/3
- 3/2
- -3/2
If, then the value of `lim_(x->0)``f(x)/x^2` is
- –2
- 0
- 1
- 2
If x = a(cos θ −log cot θ/2) , y = a sin θ, then dy/dx =
- tan θ
- −tanθ
- cot θ
- −cot θ
The integral of with respect to x is
- tan(xe^x)/(x+1)e^x)+C
- sec(xe^x)tan(xe^x)+C
- sec(xe²)+C
- tan(xe^x)+C
The slope of normal to a curve at any point (x, y) on it is -x/((x+1)y). The equation of the curve is
- y = Cxe^x
- xy=Ce^x
- xy=Ce^-x
- y²=2[log(x+1)-x]+C
The Coulomb is equal to charge on __________ electrons.
- 1.602 x 10^-19
- 6.28 x 10^-18
- 1.67 x 10^-27
- 6.18 x 10²⁸
The Ohm's laws deals with the relation between
- Charge and capacity
- Capacity and p.d.
- Charge and resistance
- Current and p.d.
One kwh is equal to __________ kCal.
- 860
- 735.5
- 36 x 10⁵
- 746
Resistivity is usually expressed in terms of
- ohm/°C
- Moh
- Ohm meter
- Ohm/cm square
Three equal resistors are connected in series across an emf source, dissipate 60 W of power. What is the power dissipated if the same resistors are connected in parallel?
- 270
- 60
- 20
- 180
The main constituents of a Portland Cement is
- lime
- Alumina
- Iron Oxide
- Alkalies
The most commonly used bond for all wall thickness is
- Flemish bond
- English bond
- Stretching bond
- Heading bond
A line normal to the plumb line at all points is known as
- Horizontal line
- Vertical line
- Level line
- Line of the collimation
In a well-conditioned triangle, no angle should be less than
- 30°
- 45°
- 60°
- 90°
A fixed point of reference of known elevation is called
- Change point
- Station point
- Bench mark
- Datum
The part which controls the air fuel ratio in a petrol engine is
- Injector
- Carburetor
- Governor
- None of these
In IC Engines the process of removing burnt gases from combustion chamber of cylinder is known as
- Supercharging
- Polymerization
- Scavenging
- Detonation
The compression ratio of Diesel engine varies from
- 15 to 25
- 10 to 15
- 6 to 10
- 25 to 40
The purpose of moderator in a nuclear power plant is
- To moderate the radioactive pollution
- To control reaction
- To reduce temperature
- To reduce the speed of fast moving neutrons
The differential is located between propeller shaft and the
- Clutch
- Engine
- Rear axle
- None of these
Name the person who was greatly influenced by the radical reformist journal of Cairo, the Al-Manar
- Moulana Abdul Kalam Azad
- Sir Sayyid Ahmed Khan
- Mohammed Abdul Rahman
- Vakkom Moulavi
Which among the following organization was founded in 1914?
- Samathwa Samajam
- Nair Service Society
- SNDP Yogam
- Yogaskhema Sabha
Which one of the following is not written by Ponkunnam Varkey?
- Vikarasadanam
- Nivedanam
- Aniyara
- Kudumbini
Name the first editor of Swadeshabhimani
- Ramakrishna Pillai
- P. Krishna Pillai
- K. P. Kesava Menon
- C. P. Govinda Pillai
Vagbhadanandha was the main disciple of
- Sree Narayanaguru
- Chattampi Swamikal
- Brahmananda Sivayogi
- V. T Bhattathiripad
Monetary Museum of Reserve Bank of India is situated at
- Kolkata
- Mumbai
- Bengaluru
- Delhi
Recently Thousand history buffs gathered in the Czech Republic to re-enact the Battle of Austerlitz. Name the ruler related with this Battle.
- Napoleon
- Henry V
- Louis XVI
- Sir Nicholas II
India made the Howitzer Artillery gun deal with
- France
- USA
- Russia
- Israel
Central Road Research Institute was established in
- 1952
- 1948
- 1956
- 1964
Who directed the Hindi filim 'Ae Dil Hai Mushkil'
- Apoorva Mehta
- Mukesh Bhat
- Karan Johar
- Yash Chopra