GaTE Model Question for EEE

Electrical Sample Questions :

1	The RMS value of the voltage u(t) =3 + 4cos (3t) is
Options	A) Ö (17) V B) 5 V C) 7 V D) (3 + 2 Ö 2 ) V
CorrectAnswer	A
2	The open loop transfer function of a unity feed back control system is given asG(s) = as + 1 s2 The value of ‘a’ to give a phase margin of 45° is equal to
Options	A) 0.141 B) 0.441 C) 0.841 D) 1.141
CorrectAnswer	C
3	The armature resistance of a permanent magnet dc motor is 0.8 W. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be
Options	A) 48.0% B) 57.1% C) 59.2% D) 88.8%
CorrectAnswer	A
4	The solution of the first order differential equation x(t) = -3x(t), x (0) = x0 is
Options	A) x (t) = x0 e-3t B) x (t) = x0 e-3 C) x (t) = x0 e-1/3 D) x (t) = x0 e-1
CorrectAnswer	A
5	The unit impulse response of a second order under-damped system starting from rest is given by c(t) = 12.5 e-6t sin 8 t,     t  0 The steady-state value of the unit step response of the system is equal to
Options	A) 0 B) 0.25 C) 0.5 D) 1.0
CorrectAnswer	D
6	A single-phase, 230 V, 50 Hz, 4 pole, capacitor-start induction motor has the following stand-still impedances Main winding Zm = 6.0 + j4.0 WAuxiliary winding Za = 8.0 + j6.0 W The value of the starting capacitor required to produce 90° phase difference between the currents in the main and auxiliary windings will be
Options	A) 176.84 mF B) 187.24 mF C) 265.26 mF D) 280.86 mF
CorrectAnswer	A
7	A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has a back emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistance is 2W. The converter is working from a 280 V, single phase ac source with a firing angle of 80°. Under this operating condition, the speed of the motor will be
Options	A) 339 rpm B) 359 rpm C) 366 rpm D) 386 rpm
CorrectAnswer	C
8	The 8085 assembly language instruction that stores the content of H and L registers into the memory locations 2050H and 2051H, respectively, is
Options	A) SPHL 2050H B) SPHL2051H C) SHLD 2050H D) STAX 2050H
CorrectAnswer	C
9	A 50 Hz, 4-pole, 500 MVA, 22 kV turbo-generator is delivering rated megavolt-amperes at 0.8 power factor. Suddenly a fault occurs reducing is electric power output by 40%. Neglect losses and assume constant power input to the shaft. The accelerating torque in the generator in MNm at the time of the fault will be
Options	A) 1.528 B) 1.018 C) 0.848 D) 0.509
CorrectAnswer	A
10	The Nyquist plot of loop transfer function G(s) H(s) of a closed loop control system passes through the point (-1, j0) in the G(s) H(s) plane. The phase margin of the system is
Options	A) 0° B) 45° C) 90° D) 180°
CorrectAnswer	D
11	A 50 kW dc shunt motor is loaded to draw rated armature current at any given speed. When driven (i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, the respective output powers delivered by the motor are approximately.
Options	A) 25kW in (i) and 75kW in (ii) B) 25kW in (i) and 50kW in (ii) C) 50kW in (i) and 75kW in (ii) D) 50kW in (i) and 50kW in (ii)
CorrectAnswer	B
12	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
Options	A) 6 B) 12 C) 16 D) 24
CorrectAnswer	D
13	For the equation x(t)+3 x(t) +2x(t) = 5, the solution x (t) approaches which of the following values as t ® ¥ ?
Options	A) 0 B) 5 2 C) 5 D) 10
CorrectAnswer	B
14	The following motor definitely has a permanent magnet rotor
Options	A) DC commutator motor B) Brushless dc motor C) Stepper motor D) Reluctance motor
CorrectAnswer	C
15	A110 kV, single core coaxial, XLPE insulated power cable delivering power at 50Hz, has a capacitance of 125 nF/km. If the dielectric loss tangent of XLPE is 2 x 10-4, the dielectric power loss in this cable in W/km is
Options	A) 5.0 B) 31.7 C) 37.8 D) 189.0
Correc Answer	D
16	The simultaneous application of signals x(t) and y(t) to the horizontal and vertical plates, respectively, of an oscilloscope, produces a vertical figure-of-8 display. If P and Q are constants, and x(t) = P sin (4t + 30), then y(t) is equal to
Options	A) Q sin (4t – 30) B) Q sin (2t + 15) C) Q sin (8t + 60) D) Q sin (4t + 30)
CorrectAnswer	B
17	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
Options	A) 13.43 kA B) 15.79 kA C) 23.25 kA D) 27.36 kA
CorrectAnswer	:B
18	Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is
Options	A) zero B) constant C) pulsating with zero average D) pulsating with non-zero average
CorrectAnswer	B
19	The equivalent circuit of a transformer has leakage reactances X1 , X
Options	A) X1>> X B) X1<< X C) X1» X D) X1» X
CorrectAnswer	D
20	If P and Q are two random events, then the following is TRUE
Options	A) Independence of P and Q implies that probability (P Q ) = 0 B) Probability (P  Q )  Probability (P) + Probability (Q) C) If P and Q are mutually exclusive, then they must be independent D) Probability (P  Q )  Probability (P)
CorrectAnswer	D

GATE Model Question for ECE

Electronics & Communication :

1 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
A) 4
B) 8
C) 16
D) 32
Answer : (B)
2 A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has a back emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistance is 2W. The converter is working from a 280 V, single phase ac source with a firing angle of 80°. Under this operating condition, the speed of the motor will be
A) 339 rpm
B) 359 rpm
C) 366 rpm
D) 386 rpm
Answer : (C)
3 In relation to the synchronous machines, which one of the following statements is false?
A) In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axis synchronous reactance
B) The damper bars help the synchronous motor self start
C) Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current
D) The V-curve of a synchronous motor represents the variation in the armature current with field excitation, at a given output power
Answer : (C)
4 A parallel plate air-filled capacitor has plate area of l0-4 m2 and plate separation of 10-3 m. It is connected to a 0.5 V, 3.6 GHz source. The magnitude of the displacement current is (e0 = 1/36p x 10-9 F/m)
A) 10 mA
B) 100 mA
C) 10 A
D) 1.59 mA
Answer : (A)
5 The 8085 assembly language instruction that stores the content of H and L registers into the memory locations 2050H and 2051H, respectively, is
A) SPHL 2050_H
B) SPHL2051_H
C) SHLD 2050_H
D) STAX 2050_H
Answer : (C)
6 If E is the electric field intensity, Ñ(Ñ x E ) is equal to
A) E
B) | E |
C) null vector
D) zero
Answer : (D)
7 The insulation strength of an EHV transmission line is mainly governed by
A) load power factor
B) switching over-voltages
C) harmonics
D) corona
Answer : (B)
8 The Q – meter works on the principle of
A) mutual inductance
B) self inductance
C) series resonance
D) parallel resonance
Answer : (C)
9 A 800 kV transmission line is having per phase line inductance of 1.1 mH/km and per phase line capacitance of 11.68 nF/km. Ignoring the length of the line, its ideal power transfer capability in MW is
A) 1204 MW
B) 1504 MW
C) 2085 MW
D) 2606 MW
Answer : (C)
10 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
A) 8/6
B) 12
C) 16
D) 8
Answer : (C)
11 At an industrial sub-station with a 4 MW load, a capacitor of 2 MVAR is installed to maintain the load power factor at 0.97 lagging. If the capacitor goes out of serivce, the load power factor becomes
A) 0.85
B) 1.00
C) 0.80 lag
D) 0.90 lag
Answer : (C)
12 The conduction loss versus device current characteristic of a power MOSFET is best approximated by
A) a parabola
B) a straight line
C) a rectangular hyperbola
D) an exponentially decaying function
Answer : (A)
13 High Voltage DC (HVDC) transmission is mainly used for
A) bulk power transmission over very long distances
B) inter-connecting two systems with the same nominal frequency
C) eliminating reactive power requirement in the operation
D) minimizing harmonics at the converter stations
Answer : (A)
14 For the equation,
s3 – 4s2+ s + 6 = 0
the number of roots in the left half of s-plane will be

A) 0
B) 1
C) 2
D) 3
Answer : (C)
15 For the function f(x) = x2 e-x, the maximum occurs when x is equal to
A) 2
B) 1
C) 0
D) -1
Answer : (B)