State Engineering Services Exam - 2017

(Model Answer Key)

Electrical Engineering

Q1 : Find the value of 'R' ( in ohms ) required for maximum power transfer in the network Shown in figure

A 2

B 4

C 8

D 16

Answer Key: C

Q2 : A 10 resistor, a 1 H inductor and 1 F capacitor are connected in parallel . The combination is driven by a unit step current.Under steady state conditions , the source current flows through

A the resistor

B the inductor

C the capacitor

D all the three elements

Answer Key: B

Q3 : Norton's theorem states that a complex network conncected to a load can be replaced with an equivalent impedance

A in series with a current source

B in parallel with a voltage source

C in series with a voltage source

D in parallel with a current source

Answer Key: D

Q4 : The condition AD - BC = 1 for a two port network implies that the network is a

A reciprocal network

B lumped element network

C lossless network

D unilateral element network

Answer Key: A

Q5 : For the circuit shown in figure quality factor Q is 25 and resonant frequency o is 50 k rad/s. Then the bandwidth B of thecircuit is

A 4 k rad /s

B 2 k rad /s

C 4.5 k rad /s

D 3 k rad /s

Answer Key: B

Q6 : Given that , then f(t) is

A

B

C

D

Answer Key: B

Q7 : For the circuit shown in figure, the hybrid parameter h21 is given as

A -2/3

B 2/3

C -1/9

D 1/9

Answer Key: A

Q8 : For which of the following materials, the relative permeability is much greater than unity ?

A Diamagnetic materials

B Paramagnetic materials

C Ferromagnetic materials

D None of the above

Answer Key: C

Q9 : Dielectric materials are essentially

A Insulating materials

B Conducting materials

C Semi conducting materials

D Ferro electric materials

Answer Key: A

Q10:

Super conductors are becoming popular for use in

A Manufacturing of memories

B Generating a very strong magnetic field

C Generating a very strong electrostatic field

D Generating regions free from magnetic field

Answer Key: A

Q11:

Power consumed by a simple dc circuit can be measured with the help of a single ammeter if

A the load resistance is known

B the supply voltage is known

C the supply current is known

D cannot be measured

Answer Key: A

Q12:

Harmonic distortions in power supply does not affect the performance of Maxwell's bridge since

A Filters are used to remove harmonics

B Final expression for unknown inductance contains only fundamental frequency

C Mechanical resonance frequency of null detectors are beyond the range of harmonic frequencies

D Final expression for unknown inductance is independent of frequency

Answer Key: D

Q13:

A meggar is used for measurement of

A low value resistance

B medium value resistance

C high value particularly insulation resistance

D All of the above

Answer Key: C

Q14:

Purely mechanical instruments cannot be used for dynamic measurements because they have

A Large time constant

B Higher response time

C High inertia

D All of the above

Answer Key: D

Q15:

The time base signal in a CRO is

A a sinusoidal signal

B a sawtooth signal

C a square wave signal

D a triangular wave signal

Answer Key: B

Q16:

Line regulation is determined by

A load current

B zener current and load current

C changes in load resistance and output voltage

D changes in output voltage and input voltage

Answer Key: D

Q17:

To saturate a BJT,

A IB = IC(sat)

B IB > IC(sat)/ dc

C Vcc must be at least 10 V

D The emitter must be grounded

Answer Key: B

Q18:

Collector - feedback bias is

A based on the principle of positive feedback

B based on the beta multiplication

C based on the principle of negative feedback

D not very stable

Answer Key: C

Q19:

A single phase fully controlled thyristor bridge rectifier is fed from a 230 V, 50 Hz single phase AC mains. If it is delivering aconstant DC current of 10 A at a firing angle of 30o, then the value of power factor at AC mains is

A 0.87

B 0.9

C 0.78

D 0.45

Answer Key: C

Q20:

The constant current region of a JFET lies between

A cutoff and saturation

B cutoff and pinch off

C 0 & IDSS

D pinch off and break down

Answer Key: D

Q21:

A single phase full bridge voltage source inverter (VSI) is fed from a 300 V battery. A pulse of 120o duration is used to triggerthe appropriate devices in each half cycle. The rms value of the fundamental component of the output voltage in volts is

A 234

B 245

C 300

D 331

Answer Key: A

Q22:

In an 8085 microprocessor system with memory mapped I/O,

A I/O devices have 16-bit addresses

B I/O devices are accessed using IN and OUT instructions

C there can be a maximum of 256 input devices and 256 output devices

D I/O devices have 8-bit addresses

Answer Key: A

Q23:

The device used to convert a binary number to a 7-segment display format is the

A Multiplexer

B Encoder

C Decoder

D Register

Answer Key: C

Q24:

In a microprocessor, when a CPU is interrupted, it

A Stops execution of instructions

B Acknowledges interrupt and branches to subroutine

C Acknowledges interrupt and continue

D Acknowledges interrupt and waits for the next instruction from the interrupting device

Answer Key: D

Q25:

An I/O processor controls the flow of information between

A cache memory and I/O devices

B main memory and I/O devices

C two I/O devices

D cache and main memories

Answer Key: B

Q26:

A 4-bit parallel adder can add

A two 4-bit binary numbers

B two 2-bit binary numbers

C four bits at a time

D four bits in a sequence

Answer Key: A

Q27:

The number of hard ware interrupts present in 8085 microprocessor are

A 1

B 4

C 5

D 13

Answer Key: C

Q28:

An asynchronous counter differs from a synchronous counter in

A the number of states in its sequence

B the method of clocking

the type of flip-flops used

C

D the value of the modules

Answer Key: B

Q29:

A modulus -10 ring counter require a minimum of

A ten flip-flops

B five flip-flops

C four flip-flops

D twelve flip-flops

Answer Key: A

Q30:

A ROM is a

A nonvolatile memory

B volatile memory

C read / write memory

D byte - organized memory

Answer Key: A

Q31:

The phenomenon of overlap in converter operation occurs due to

A source resistance

B source inductance

C both source resistance and source inductance

D high value of firing angle

Answer Key: B

Q32:

The average load current supplied by a thyristor depends on

A firing angle

B firing frequency

C magnitude of gate current

D all of the above

Answer Key: A

Q33:

In register index addressing mode, the effective address is given by

A the index register value

B the sum of the index register value and the operand

C the operand

D the difference of the index register value and the operand

Answer Key: A

Q34:

The characteristic equation of a feed back control system is given by 3s4 + 10s3 + 5s2 + 5s + 2 = 0. The number of roots in theRHP of the s-plane are

A zero

B 1

C 2

D 3

Answer Key: C

Q35:

A unity feedback system has open loop transfer function . The peak overshoot in the step input response of the

system is approximately equal to

A 5%

B 10%

C 15%

D 20%

Answer Key: B

Q36:

Consider the root locus plot of a unity feedback system with open loop transfer function.

.

The meeting point of the asymptotes on the real axis occurs at

A -1.2

B -0.85

C -1.05

D -0.75

Answer Key: D

Q37:

In a constant v/f induction motor drive, the slip at the maximum torque

A is directly proportional to the synchronous speed

B remains constant with respect to the synchronous speed

C has an inverse relation with the synchronous speed

D has no relation with the synchronous speed

Answer Key: C

Q38:

No load current in a transformer

A lags the applied voltage by 90o

B lags the applied voltage by somewhat less than 90o

C leads the applied voltage by 90o

D leads the applied voltage by somewhat less than 90o

Answer Key: B

Q39:

On the two sides of a star/delta transformer

A the voltages and currents are both in phase

B the voltages and currents both differ in phase by 30o

C the voltages differ in phase by 30o but currents are in phase

D the currents differ in phase by 30o but voltages are in phase

Answer Key: B

Q40:

Short - pitching armature winding in an AC machine

A increase phase voltage but reduces its harmonic content

B increase phase voltage and its harmonic content

C reduces phase voltage and its harmonic content

D reduces phase voltage but increase its harmonic content

Answer Key: C

Q41:

Field control of a DC shunt motor gives

A constant torque drive

B constant power drive

C constant speed drive

D variable load speed drive

Answer Key: B

Q42:

In a synchronous machine, the voltage induced by armature reaction flux acts like

A The voltage drop in inductive reactance

B The voltage drop in resistance

C The voltage drop in capacitive reactance

D None of the above

Answer Key: A

Q43:

Given Xd = d - axis synchronous reactance,Xq = q - axis synchronous reactance.In a salient pole synchronous machine

A Xq > Xd

B Xq = Xd

C Xq < Xd

D Xq = 0

Answer Key: C

Q44:

By adding a resistance in the rotor circuit of a slip ring induction motor

A The starting current and torque both reduce (compared to DOL start)

B The starting current and torque both increase

C The starting current reduces but starting torque increases

D The starting current increases but starting torque decreases

Answer Key: C

Q45:

A capacitor start single phase induction motor is used

A For easy to start loads

B For medium start loads

C For hard to start loads

D For any type of start loads

Answer Key: C

Q46:

If the length of a cable is doubled, its capacitance

A Becomes one-fourth

B Becomes one-half

C Becomes double

D Remaines unchanged

Answer Key: C

Q47:

The arc voltage produced in AC circuit breaker is always

A In phase with the arc current

B Lagging the arc current by 90o

C Leading the arc current by 90o

D None of the above

Answer Key: A

Q48:

Burden of a protective relay is the power

A required to operate the circuit breaker

B absorbed by the circuit of relay

C developed by the relay circuit

D None of the above

Answer Key: B

Q49:

A synchronous condenser is

A an induction motor

B under excited synchronous motor

C over excited synchronous motor

D DC generator

Answer Key: C

Q50:

The FACTS device which uses voltage source converter in it is

A TCSC

B SVC

C TCR

D SSSC

Answer Key: D

Q51:

The sinusoidal signal x(t) = 2 cos( t) can be expressed as follows:

A ej t + e-j t

B ej t - e-j t

C (ej t - e-j t)/j

D (ej t + e-j t)/j

Answer Key: A

Q52:

The Laplace transform of integral of u(t-6) is given by (Here u(t) is an unit step function) :

A e-6s/s

B e-6s

C e-6/s

D -e-6s/s

Answer Key: A

Q53:

The signal x(t) = Acos( t + ) is:

A Energy signal

B Power signal

C Energy and power signed

D None of the above

Answer Key: B

Q54:

If X(s) is the one-sided Laplace transform of x(t), then, the Laplace transform of is given by

A (X(s) - x(0))/s

B X(s)

C X(s)/s

D sX(s) - x(0)

Answer Key: C

Q55:

The condition for a stable system in z - domain can be given as

A |z| > 1

B |z| < 1

C |z| = 1

D |z| 1

Answer Key: B

Q56:

If impulse response for a linear time invariant system is , then what will be the output of this system wheninput signal to this system is u[n]?

A

B

C

D

Answer Key: A

Q57:

The autocorrelation function of the signal x(t) denoted by follows the following property:

A

B

C

D

Answer Key: B

Q58:

The other name of common collector amplifier is

A Source follower

B Collector follower

C Emitter follower

D Base follower

Answer Key: C

Q59:

A low pass filter can behave as follows:

A Differentiator

B Integrator

C Differentiator and integrator

D Neither Differentiator nor integrator

Answer Key: B

Q60:

Common mode rejection ratio (CMRR) for an operational amplifier should have value

A Equal to 1

B Near to 1

C Very less

D As maximum as possible

Answer Key: D

Q61:

In operational amplifier circuit, suppose we ground non-inverting input, in that case the inverting input

A Becomes zero

B Behaves like a virtual ground

C Becomes very high

D None of the above

Answer Key: B

Q62:

In a 100 bus power system ,there are 10 generators. In Particular iteration of Newton Raphson load flow technique (in polar co-ordinates), two of the PV buses are converted to PQ type. In this iteration ,

A The number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two

B the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two

C The number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two

D the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two

Answer Key: B

Q63:

The Poynting vector in terms of electric field vector and magnetic field vector is given by

A

B

C

D

Answer Key: D

Q64:

Maxwell's equation in free space can be given as:

A

B

C

D

Answer Key: C

Q65

:

If two sinusoidal vectors with different amplitudes and phases are added together, then the resulting vector is polarized

A Linearly

B Elliptically

C Circularly

D None of the above

Answer Key: B

Q66:

The Boolean expression given by is equivalent to the following

A X+Y

B

C XY

D

Answer Key: A

Q67:

The Boolean expression A = Z(Y+Z) (X+Y+Z) can be simplified to

A X

B Y

C Z

D XY

Answer Key: C

Q68:

In JK flip flop, the race round condition takes place when,

A J=0,K=0

B J=0,K=1

C J=1,K=0

D J=1,K=1

Answer Key: D

Q69:

The half adder circuit has the following number of inputs and outputs respectively

A 1,2

B 2,1

C 2,2

D 2,3

Answer Key: C

Q70:

Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at anover excited condition and a directly grid connected induction generator. Consider capacitive VAr to be source and inductive VArto be sink of reactive power. Which one of the following statement is true ?

A Synchronous motor and synchronous generators are sources and induction generator is a sink of reactive power

B Synchronous motor and induction generator are sources and synchronous generator is a sink of reactive power.

C Synchronous motor is a source and induction generator and synchronous generator are sinks of reactive power

D All are sources of reactive power

Answer Key: A

Q71:

The lag compensator can be considered as:

A A low pass filter

B A high pass filter

C A band pass filter

D A band stop filter

Answer Key: A

Q72:

Transducer is a device which is

A Useful for converting power from one form to other form

B Useful for converting energy from one form to other form

C Useful in measurement of electrical signals

D Useful in amplification of the signals

Answer Key: B

Q73:

In an ideal Ammeter, the internal resistance should be

A Infinite

B High value

C Zero

D Medium

Answer Key: C

Q74:

The following bridge can be used for measuring the dielectric loss of the capacitor

A Owen bridge

B Wien bridge

C Schering bridge

D Maxwell bridge

Answer Key: C

Q75:

Q-meter works on the following principle:

A Parallel resonance circuit

B Series resonance circuit

C Mutual inductance

D Self inductance

Answer Key: B

Q76:

If two signals denote by x1(t) and x2(t) are orthogonal then the following condition is satisfied:

A

B

C

D

Answer Key: A

Q77:

Pre emphasis in frequency modulated (FM) communication system is generally used for

A Amplifying low-frequency components

B Amplifying high-frequency components

C Amplifying low and high frequency components

D Amplifying DC component

Answer Key: B

Q78:

A linear discrete time system has the characteristic equation, z3-0.81z = 0. The system is

A Stable

B Marginally Stable

C Unstable

D Stability cannot be assessed from the given information

Answer Key: A

Q79:

The following modulation system requires minimum channel bandwidth:

A Vestigial side band (VSB)

B Double side band suppressed carrier (DSB-SC)

C Single side band (SSB)

D Amplitude modulation (AM)

Answer Key: C

Q80:

In television system, the following modulation schemes are used for picture and sound respectively

A Frequency modulation, Amplitude modulation

B Amplitude modulation , Frequency modulation

C Amplitude modulation, Amplitude modulation

D Frequency modulation, Frequency modulation

Answer Key: B

Q81:

The following type of system can be represented in unique way with the help of transfer function:

A Linear time - variant systems

B Non linear time - variant systems

C Non linear time - invariant systems

D Linear time - invariant systems

Answer Key: D

Q82:

The transfer function of a system is given by . What will be the gain for frequency =6,

A 1

B 2

C 3

D 4

Answer Key: B

Q83:

The phase cross over frequency is derived where the phase angle has following value:

A - radian

B radian

C /2 radian

D 0

Answer Key: B

Q84:

The phase margin of a stable feedback system is

A Always negative

B Always positive

C May be positive or negative

D None of the above

Answer Key: B

Q85:

The following type of systems has tendency to generate oscillations:

A Closed loop system

B Open loop system

C Open and closed loop system

D None of the above

Answer Key: A

Q86:

In Amplitude Modulation (AM) communication systems, the oscillator frequency in receiver is as:

A Always 455 Hz

B More than signal frequency

C Less than signal frequency

D Same as signal frequency

Answer Key: B

Q87:

Quantization error takes place in the following process:

A Pulse width modulation

B Pulse code modulation

C Frequency division multiplexing

D Time division multiplexing

Answer Key: B

Q88:

The Quantization noise can be reduced by

A Using radio frequency amplifier in the receiver

B Increasing number of quantization levels

C Sending sloping pulses

D Applying de-emphasis circuit

Answer Key: B

Q89:

In Amplitude modulation (AM) system, a carrier is modulated by two sinusoidal message signals with modulation index of 0.6and 0.8 respectively. Then, the resulting modulation index will be as:

A 1.4

B 0.8

C 1.0

D 0.2

Answer Key: C

Q90:

In the amplitude modulation (AM) communication system, the modulation index should be in the following range:

A 0 to 1

B -1 to 1

C 1 to 2

-1 to 0

DAnswer Key: A

Q91:

For a narrow-band frequency modulated (FM) signal, the generated bandwidth for 5 KHz audio signal will be

A 5 KHz

B 10 KHz

C 20 KHz

D 30 KHz

Answer Key: B

Q92:

If signal energy (E) satisfies the following condition 0 < E < , then this signal will be called as:

A Energy signal

B Power signal

C Stationary signal

D Non-stationary signal

Answer Key: A

Q93:

For two events A and B that are independent and mutually exclusive then the probability P(AB) will be

A 1

B 0

C

D 0.5

Answer Key: B

Q94:

The mean of the random processZ(t)= Y(t)- Y(t-T) can be given as

A 1

B 0

C T

D 2T

Answer Key: B

Q95:

The following statement is true:

A JFET can be represented as a current controlled current source

B JFET can be represented as a current controlled voltage source

C JFET can be represented as a voltage controlled voltage source

D JFET can be represented as a voltage controlled current source

Answer Key: C

Q96:

Nyquist rate (NR) of the signal and maximum frequency (MF) are related as:

A NR = MF

B NR = 2MF

C NR = 1/MF

D NR = MF/2

Answer Key: B

Q97:

Ripple factor is defined as:

A RMS Value / Peak value

B Peak value / RMS value

C Peak Value / DC value

D RMS Value / DC value

Answer Key: D

Q98:

Diffraction in electromagnetic waves takes place due to

A Spherical waveforms

B Edge of a sharp obstacle

C Waves pass through a large slot

D Reflections from the ground

Answer Key: B

Q99:

In parabolic reflector, the Cassegrain feed is used for the following purpose:

A In order to make high gain of the system

B In order to make higher bandwidth of the system

C In order to decrease size of the main reflector

D In order to place the feed at a convenient point

Answer Key: D

Q100

:

A PIN diode finds application as

A Microwave switch

B Microwave detector

C Microwave mixer diode

D Metal semiconductor point-contact diode

Answer Key: A