End Test Now
A master-slave flip-flop has the characteristic that
Change in the input immediately reflected in the output
Change in the output occurs when the state of the master is affected
Change in the output occurs when the state of the slave is affected
Both the master and the slave states are affected at the same time
A digital-to-analog converter with a full-scale output voltage of 3.5 V has a resolution close to 14m V. Its bit size is
4
8
16
32
The phase velocity of an electromagnetic wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is
Equal to its group velocity
Less than the velocity of light in free space
Equal to the velocity of light in free space
Greater than the velocity of light in free space
An ideal op-amp is an ideal
voltage controlled current source
voltage controlled voltage source
current controlled current source
current controlled voltage source
Which one of the following filters has highest Q (Quality Factor)
Mechnical Filter
Garnet Filter
Atomic Filter
Quartz Filter
The 8085 assembly language instruction that stores the content of H and L registers into the memory locations 2050H and 2051H, respectively, is
SPHL
SHLD
STAX
What is the primary function of multiplexing?
To match the frequency range of a signal to a particular channel.
To reduce the bandwidth of a signal.
To select one radio channel from a wide range of transmitted channels.
To allow a number of signals to make use of a single communications channel.
Colpitts oscillator is an electrical dual of
Hartley Oscillator
Clapp Oscillator
Pierce Oscillator
Armstrong Oscillator
The bandgap of Germanium at room temperature is
1.3 eV
0.7 eV
1.1 eV
1.4 eV
In a PCM system, if the code word length is increased from 6 to 8 bits, the signal to quantization noise ratio improves by the factor
8/6
12
Which of the following is not included in the process of reception
Decoding
Encoding
Storage
Interpretation
One of the following types of noise becomes of great importance at high frequencies beyond GHz ranges. It is the
Shot noise
Impulse noise
Random noise
Transit–time noise
A carrier wave is simultaneously modulated by two sine wave with modulation indices of 0.3 and 0.4. The total modulation index will be
1
Cannot be calculated unless phase relation is known
0.5
0.7
One of the following cannot be used to remove the unwanted sideband in SSB modulation. It is the
Filter method
Phase-shift method
Third method
Balanced modulator
Indicate which one of the following is not an advantage of FM over AM
Better noise immunity is provided
Lower bandwidth is required
The transmitted power is more useful
Less modulating power is required
A super heterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency in this case would be
750 kHz
900 kHz
1650 kHz
2100 kHz
Indicate the false statement. The SWR on a transmission line is infinity; the line is terminated in
a short circuit
a complex impedance
an open circuit
a pure reactance
For the equation, , the number of roots in the left half of s-plane will be
0
2
3
The noise voltage across a resistor maintained at an absolute temperature T
is directly proportional to the Resistance
is directly proportional to the square of the resistance
is directly proportional to the square root of the resistance
is directly proportional to the bandwidth of measurement
If the noise figure and gain of the three stages of a three stage amplifier are , and respectively. The overall noise figure of the amplifier will be
4.6
6
6.6
11.6
The dominant mode of propagation is preferred with rectangular waveguides because (indicate the false statement)
It leads to smallest waveguide dimensions
The resulting impedance can be matched directly to coaxial lines.
It is easier to excite than the other modes
propagation of it without any spurious generation can be ensured
The Shannon-Hartley law:
refers to distortion
defines bandwidth
describes signaling rates
refers to noise
The primary purpose of the helix in a Travelling Wave Tube (TWT) is to:
Prevent the electron beam from spreading in the long tube
Reduce the axial velocity of the RF field
Ensure broadband operation
Reduce the Noise Figure
A non degenerate parametric amplifier has an input frequency and a pump frequency . The idler frequency is:
Indicate which of the systems is digital:
pulse position modulation
pulse code modulation
pulse width modulation
pulse frequency modulation
Biggest disadvantage of PCM is:
Its inability to handle analog signals
the higher error rate which its quantizing noise introduces
its incompatibility with TDM
the large bandwidth that are required for it
Full duplex operation:
requires two pairs of cables
can transfer data in both directions at once
requires modems at both ends of the circuit
all of the above
The maximum power that may be handled by a ferrite component at microwave frequencies is limited by the:
Curie Temperature
Saturation Magnetisation
Line Width
Gyrometric Resonance
Telephone traffic is measured:
With echo cancellers
By the relative congestion
In terms of the grade of service
In Erlangs
The Field Effect Transistors has following characteristics:
Its operation depends on flow of majority carriers only.
It exhibits low input resistance
It is more noisy than a BJT
All of the above
The term power budgeting in optical communication refers to:
The cost of cable, connecters, equipment, and installation
loss of power due to defective components
Total power available minus the attenuation losses
comparative costs of fiber and copper installations
Interlacing is used in television to:
produce the illusion of motion
ensures that all the lines on the screen are scanned, not nearly the alternate ones
simplify the vertical sink pulse train
avoid flicker
The terms single mode and multi mode in optical fiber are best described as:
The number of fibers placed into a fiber optic cable
number of voice channels each fiber can support
number of wavelengths each fiber can support
the index number
The code which provides for parity checks is:
Baudot
EBCDIC
ASCII
CCITT-2
The basic requirement of a dc armature winding is that it must be
Closed one
Lap winding
Wave winding
Either (b) or (c )
A hydraulic turbine having rated speed of 250 rpm is connected to a synchronous generator. In order to produce power at 50 Hz, the number of poles required in the generator are: -
24
The following motor definitely has a permanent magnet rotor
DC commutator motor
Brushless dc motor
Stepper motor
Reluctance motor
A 500 MW 3-phase Y-connected synchronous generator has a rated voltage of 21.5 kV at 0.85pf. The line current when operating at full load rated conditions will be
13.43 kA
15.79 kA
23.25 kA
27.36 kA
Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is
Zero
Constant
Pulsating with zero average
Pulsating with non-zero average
In relation to the synchronous machines, which one of the following statements is false?
In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axis synchronous reactance.
The damper bars help the synchronous motor self-start.
Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current.
The V-curve of a synchronous motor represents the variation in the armature current with field excitation, at a given output power.
A bipolar junction transistor (BJT) is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT
Both the base-emitter and base-collector junctions are reverse biased.
The base-emitter junction is reverse biased, and the base-collector junction is forward biased.
The base-emitter junction is forward biased, and the base-collector junction is reverse biased.
Both the base-emitter and base-collector junctions are forward biased.
The Q – meter works on the principle of
Mutual inductance
Self inductance
Series resonance
Parallel resonance
The series field of a short shunt dc generator is excited by _______ currents.
shunt
armature
load
external
The conduction loss versus device current characteristic of a power MOSFET is best approximated by
a parabola
a straight line
a rectangular hyperbola
an exponentially decaying function
A digital-to-analog converter with a full-scale output voltage of 3.5 V has a resolution close to 14 mV. Its bit size is
The output voltage waveform of a three-phase square-wave inverter contains
Only even harmonics
Both odd and even harmonics
Only odd harmonics
Only triple harmonics
In dc generators, the effect of armature reaction on the main pole flux is to
Reduce it
Distort it
Reverse it
Both a & b
The following terms used in the context of an instrument are numbered as shown: (i) accuracy, (ii) sensitivity, (iii) precision and (iv) resolution Match these with their possible definitions listed belowP. Repeatability of readings on successive observations Q. Smallest perceptible change in the output R. Deviation of the output from the true value S. Minimum value of the input from the true value T. Ratio of the change in the instrument reading to the change in the measured variable.
1-P, 2-Q, 3-R, 4-S
1-S, 2-Q, 3-P, 4-T
1-R, 2-T, 3-P, 4-Q
1-T, 2-Q, 3-P, 4-R
An amplifier of gain 10, with a gain-bandwidth product of 1 MHz and slew rate of 0.1 V/s is fed with a10 KHz symmetrical square wave of 1 V amplitude. Its output will be
Binary means….....
Three
Four
Two
None of the above.
The digits used in a binary number system are ……... and ……...
9 and 0
0 and 1
1 and 2
None of the above
The clock signals are used in sequential logic circuits
To tell the time of the day
To tell how much time has elapsed since the system was turned on
To synchronize events in various parts of a system
The 3-dB cut-off frequency of a first analog high pas filter is the output will have a phase shift of
A 3 1/2 digit multimeter has an accuracy specification of ( 0.5% of reading 5 counts). If the meter reads 2.00 mA on a full scale of 20mA, the worst-case error is
0.5%
2.5%
3.0%
5.5%
Consider the following systems: System 2: G(s) = 1/2(2S + 1) System 1: G(s) = 1/2(5S + 1)The true statement regarding the system is
Bandwidth of system 1 is greater than the bandwidth of system 2.
Bandwidth of system 1 is lower than the bandwidth of system 2.
Bandwidth of both the systems are the same.
Bandwidth of both the systems are infinite.
Three DC currents meet at a node with entering and leaving the node. are measured as 100mA and 99 mA with a 1% accuracy. Then the value of and the accuracy of are
1 mA 20%
199 mA 2%
1 mA 2%
1 mA 199%
As compared to oscillators, inverters provide
Distorted o/p
Highly stabilized o/p
Low freq o/p
Two copper-constantan thermocouples are connected such that the two constantan wires are joined together. The two copper wires are connected to the input of a low noise chopper stabilized differential amplifier having a gain of 1000. One of the thermocouple junctions is immersed in a flask containing ice and water in equal proportion. The other thermocouple is at a temperature T. If the output of the amplifier is 2.050V, the temperature T is
For a first order instrument a 5% settling time is equal to
Three times the time constant.
Two times the time constant.
The time constant.
Time required for the output signal to reaches 5% of the final value.
A twisted pair of wires is used for connecting the signal source with the instrumentation amplifier, as it helps reducing
The effect of external interference.
The error due to bias currents in the amplifier.
The loading of the source by the amplifier.
The common mode voltage.
A second order feedback system is found to be oscillating with a high frequency. The oscillations
Can be reduced by increasing the proportional action.
Can be reduced by increasing the integral action.
Can be reduced by increasing the derivative action.
Cannot be reduced.
Change in the input immediately reflected in the output.
Change in the output occurs when the state of the master is affected.
Change in the output occurs when the state of the slave is affected.
Both the master and the slave states are affected at the same time.
The cascade amplifier is a multistage configuration of
CC-CB
CE-CB
CB-CC
CE-CC
A phase lag compensation coil
Improves relative stability
Increases bandwidth
Increases overshoot
A device with input x (t) and output y (t) is characterized by: y (t) = (t). An FM signal with frequency deviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth of the output signal is
370 kHz
190 kHz
380kHz
95kHz
Meggar is an instrument used for measuring
current
voltage
insulation resistance
power
Which of the following is a scalar quantity
velocity of a gear
acceleration of a car
force in friction
area of a triangle
Separation of flow is caused by
reduction of pressure in the direction flow
decrease in the boundary layer thickness
I ncrease of velocity in the direction of flow
adverse pressure gradient
A pitot tube senses
stagnation pressure
average pressure
maximum pressure
velocity head pressure
The Bernoulli’s equation talks about
Energy transfer from one form to another
Energy and mass transfer
Mass transfer of fluids
The process in which pressure & density decrease where as the velocity increase are known as following regions :
Expansion
Compression
Neutral
None of these
A closed cycle gas turbine works on
Carnot cycle
Rankine cycle
Brayton cycle
Joule cycle
Diffuser must provide minimum
Pressure loss
Velocity loss
Density loss
Best suited Gas turbine engine for aircraft is
Constant Pressure
Constant volume
Combination of a & b
Free turbine is used in
Turbo jet and Turboprop
Turbofan and Turboprop
Turboprop and Reciprocating
Turboprop and Turboshaft
In case of a rocket engine the mixture of fuel and oxidiser is called
Oxygen fuel
Oxidiser
Propellent
ATF
Turbojet engine produces thrust by
acclerating large mass of gas through small velocities
acclerating small mass of gas through small velocities
acclerating small mass of gas through large velocities
none of the above
Aircraft thrust is generated based on principle of
Newtons first law
Charles Law
Newtons Third law
The combustion is initiated in a gas turbine engine by
Igniter Plug
Spark Plug
Torch Igniters
both (a) and©
The maximum temperature in combustion chamber of a typical aircraft engine is
850 deg to 1700 deg C
100 deg to 200 deg C
300 deg to 500 deg K
None of these.
In a gas turbine, the combustion of fuel and air is carried out in
Combustion chamber
Compressor
Turbine
In centrifugal flow compressor inlet flow is taking place in
Axial direction
Radial direction
Both (a) and (b)
The combination of rotors and stators is found in
Axial flow compressors
Centrifugal flow compressors
Reciprocating compressors
Which of the following forces are called axial forces?
Shear and compression
Torsion and shear
Tension and shear
Tension and compression
The free turbine configuration is used in
Turbo prop and turbo shaft
Turbo jet
Pulse jet
Ram jet
Stress is a
Vector
Scalar
Tensor
Special scalar
The mechanism used in petrol engine is
Crank mechanism
Slider mechanism
Slider crank mechanism
Natural lines and circular
Reynolds No. may be defined as the ratio of
Inertial forces to Viscous forces
Elastic forces to pressure forces
Viscous forces to gravity forces
Aerofoil shape is imparted to the aircraft wing by structures known as
Longerons
Stringers
Ribs
Spars
In multistage turbines by introducing reheating
Thermal efficiency improves
The output of turbine increases
Work done by compressor reduces
The ratio compressor work/turbine decreases
In Jet engine the compression ratio
Varies with altitude
Varies with square of speed
Varies as cube of speed
remains constant
Gas turbine used in aircraft is of
Open cycle type
Closed cycle type with reheating
Closed cycle type with reheating and regeneration
Open cycle type with reheating, regeneration and intercooling
Stress concentration occurs when
A body is subjected to excessive stress
A body is subjected to unidirectional stress
A body is subjected to fluctuating stress
A body is subjected to non uniform stress distribution
The inability of a body to change its state of rest or uniform motion along a straight line is called its
Momentum
Velocity
Acceleration
Inertia
A material subjected to reversal of stresses does not fail at a stress known as
fatigue stress
Proof stress
Safe stress
Endurance stress
In simple harmonic motion the acceleration is proportional to
Displacement
Linear velocity
Angular velocity
Rate of change of angular velocity
The relation Stress/Strain is called as
Youngs modulus
Rigidity modulus
Shear modulus
Poisson’s ratio
Resistance offered by a body against external distorting force is called
strain
stress
shear strain
modulas
Inviscid and incompressible flow means
Viscosity and pressure are constant
Viscosity is zero and density is constant
Viscosity is constant and density is zero
In a structure bending moment is maximum when
Shear force is maximum
Shear force is zero
Axial force is zero
Axial force is maximum
LP and HP compressors are coupled
Rigidly by shaft
Thermodynamically
Aerodynamically
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