APSPDCL AE PAPER - 2010

1.         A series circuit has 3Ω, 30Ω and 20Ω and 2 V DC in series. If 2Ω resistor is replaced by open circuit, the current in the circuit is                                          
(1) Zero  (2) increased (3) decreased  (4) constant

 2.The peak of conductance curve of a series RLC circuit occurs at                       
(1) Zero frequency      (2) below the resonant frequency    (3) resonant frequency    (4) above the resonant frequency

 3.Maximum power transfer takes place at an efficiency of                                    
(1) 25% (2) 75% (3) 50% (4) 100%

 4.Gauss law is
(1) del . D = 0 (2) del D = ρ_v    (3) del . D =E (4) del . D = H

 5.Electric field has the units of
(1) V/m (2) V-M (3) weber (4) Gauss

 6. Potential due to a point charge at infinite distance is
(1) Zero (2) infinity (3) large (4) small

 7. Capacitance of a capacitor depends on
(1) applied charge (2) applied voltage  (3) applied field (4) geometrical physical parameters

 8. The del operator has
(1) no units (2) units of m^-1  (3) units of m  (4)  units of second

 9. For DC voltage, inductor behaves as
(1) open circuit (2) short circuit    (3) voltage source (4) current source

 10. Ideal diode is characterized by
(1) Infinite resistance (2) Zero resistance   (3) 10MΩ  (4) 500KΩ

 11. The knee voltage of silicon diode is
(1) 1.0 V (2) 0.7V (3) 0.7 mV (4) 0.3V

 12. The peak inverse voltage of each diode in bridge rectifier is
(1) 4Vm (2) 2Vm   (3) Vm (4) Vm / G

 13. Voltage gain of BJT amplifier is 
(1) A_i R_L  (2) A_i R_L / R_i  (3) A_i R_i / R_L  (4) A_iR_i

 14. JFET is
(1) voltage controlled device (2) current controlled device (3) resistance controlled device (4) conductance controlled device

 15. Frequency response of an ideal voltage amplifier is

 16. Negative feedback leads to
(1) more stability (2) more gain (3) less gain (4) less bandwidth

 17. Pulse generator is
(1) Astable multivibrator (2) monostabe multivibrator (3) bistable multivibrator (4) Schmitt trigger

 18. Ideal operational amplifier has
(1) Infinite input resistance (2) Infinite output resistance (3) small gain (4) small bandwidth

 19.IC 8255 programmable peripheral interface mode 1 is
(1) Basic I/O mode   (2) Strobed I/O mode (3) BSR mode (4) Parallel processing mode

 20. The number of comparators needed to build a 6-bit simultaneous A/D converter (1) 63 (2) 7 (3) 6 (4) 64

 21.The slew rate S/H circuit must be
(1) high (2) one (3) low (4) zero

 22.In 8085 microprocessor memory write cycle takes ----T-states
(1) 2 (2) 3 (3) 4 (4) 1

 23.The CALL instruction requires the following T-states
(1) 3 (2) 18 (3) 1 (4) 5

 24.The no. of comparators needed to build a 6-bit counter type A/D converter
(1) 64 (2) 32 (3) 6 (4) 1

 25.Which of the following is the fastest A/D converter
(1) counter type A/D   (2) successive approximation (3) dual type (4) integrating type

 26.What is the maximum output voltage of 8-bit D/A converter with 10V supply
(1)9.961V      (2)9.691V      (3)10V          (4)5V

 27.The discrete time signal is a function which the independent variable is             
(1) discrete (2) analog (3) either discrete or analog (4) continuous

 28.A signal is a periodic signal with period T is x(t) is equal to 
(1) x(-t) (2) x(1/t) (3) x(t+T) (4) x(T)

 29.The signal anu(n) is neither an energy signal nor a power signal if
(1)  | a | > 1   (2) |a| <1 (3) |a| = 0 (4) (1) |a| = 1

 30.In a periodic signal, if the period T_o is doubled, the fundamental frequency ω_o in the spectrum will
(1)  double (2)  halve (3)  increase by u times (4) not change

 31.A function x(t) is said to be odd if x(-t) is equal to
(1) x(-t)    (2) x(2t)    (3) x(-2t)    (4) –x(t)

 32.What is a spectrum of a dc signal?
(1) 0     (2) 1    (3) 2π     (4) 2πδ(ω)

 33.Spectrum of a periodic pulse is
(1) continuous sync.Function  (2) discrete sync. Function (3) pulse train (4) impulse function

 34.Fourier transform of the unit impulse δ(t)
(1) 0 (2) π (3) 1 (4) δ(ω)

 35.The Fourier transform of signal x(-t) is 
(1) –X(ω) (2) X(-ω) (3) –X(-ω) (4) X(ω)

 36.The Laplace transform of e^5t f(t) is 
(1) F(s)  (2) F(s-1) (3) F(s/5) (4) F(s-5)

 37. The final value of  2s+1 / s⁴+8s³+16s²+s 
(1) 2 (2) infinite (3) Zero (4) 1

 38. The inverse Laplace transform of   1(1-e^-as) /s 
(1) u(t) –u(t-a)  (2) u(t)  (3) u(t-a) (4) Zero

 39.The z-transform of naⁿu(n) is 
(1) az / (z-a)  (2) az / (z-a)²    (3) a/ (z-a)²  (4) z/ (z-a)²

 40. For calculating convolution integral, shifting function must be folded about the
(1) y-axis (2)  x-axis (3) z-axis (4) Zero axis

 41.The armature of a DC machine is made up of laminated sheets to                       
(1) reduce hysteresis loss (2) reduce eddy-current loss (3) reduce armature copper loss (4) increase dissipation of heat from the armature surface

 42. The maximum permissible operating temperature of class-E insulating material is
(1) 130⁰C (2) 180⁰C (3) 120⁰C (4)105⁰C

 43.The number of parallel paths in armature winding of a four pole wave connected Dc machine having 22 coil sides is
(1) 4 (2) 2 (3) 22 (4) 1

 44. Two transformers with leakage impedance Z₁=0.1+j0.4 and Z₂=0.05+j0.2 are connected in parallel. The ratio of loads shared will be
(1) equal (2) 1 :2 (3) 2:1 (4) 2:3

 45. In a transformer, all-day efficiency
(1) is higher than the full-load efficiency (2)  is maximum efficiency (3) is lower than the full- load efficiency (4) None of these

 46. A 50Hz 3-phase induction motor has a full-load speed of 1440rpm. The number of poles of the motor is
(1) 4 (2)  6 (3) 12 (4) 8

 47. A 3-phase cage rotor induction motor has its stator wound for 8 poles. The rotor of this motor can be used in any other induction motor of the same size and having
(1) 4 poles (2)  8 poles (3) 2 poles (4) any number of poles

 48. Under blocked rotor condition the frequency of rotor currents in a 50Hz 3-phase induction motor is
(1) very low (2) Very high (3) 50 (4) about 50

 49.At s=0 the torque of an induction motor is
(1) 0 (2) equal to full load (3) very high (4) nearly zero

 50.A 3-phase induction motor takes a line current of 30A when started by direct switching If a star –delta starter is used, the line current would be
(1) 30A (2) 17.32A (3) 10A (4) 5A

 51. In order to minimize both the 5^th and 7^th harmonics, the coil-span must be
(1) 144⁰ (2) 6/7 pole-pitch (3) 5/6 pole-pitch (4) 120⁰

 52. For a fixed load on the shaft, the armature current of a synchronous motor is minimum when the power factor is
(1) Less than 1 and leading (2) unity (3) lagging (4) leading or lagging but not unity

 53. Graphite is used in nuclear power plant as a
(1) Fuel (2) coolant (3) moderator (4)electrode

 54. Distributed parameter models for transmission lines must be considered if there are
(1) <100 Km (2) > 100Km < 150 Km  (3) 50Km (4) >250  Km

 55. The undesirable effects of corona are
(1) Power loss (2) harmonic currents (3) radio interference (4) all 1, 2 and 3

 56. Which portion of the power system is least prone to faults?
(1) Alternator (2) Switchgear (3) Transformers (4) overhead lines

 57. The important requirements of a good distribution system are
(1) reliability (2) proper voltage (3) both a and b (4) feeders

 58. The per unit impedance of a circuit element is 0.15.  If the base KV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be
(1) 0.075 (2) 0.15 (3) 0.30 (4) 0.60

 59. Which of the following comes under operational cost of power system
(1) fuel cost (2) labor cost (3) both 1 and 2 (4) interest and taxes

 60. The bus at which the real and reactive powers are not specified, is
(1) slack bus (2) load bus (3) generator bus (4) impedance bus

 61. In a balanced three phase system, negative and zero phase sequence currents are 
(1) equal (2) Zero (3) Different (4) One

 62. The phase sequence of the positive sequence component is RYB, then the phase sequence of the negative  sequence components will be
(1) RYB (2) YRB (3) RBY (4) BRY

 63. Buchholtz relay is used in protection of 
(1) Transmission lines (2) Circuit breakers (3) Transformers (4) Generators

 64. In inverse time over current  relays, the current time characteristics are
(1) Parabolic (2) Exponential (3) linear (4) Hyperbolic

 65. The solution of point by point method adopted to solve the swing equation for
(1) Power angle (2) critical clearing time (3) clearing angle (4) clearing time

 66. A system which follows the superposition principle is known as
(1) System (2) Control system (3) Linear system (4) unilateral system

 67. Area under a unit impulse function is
(1) Infinity (2) Zero (3) unity (4) large

 68. Laplace transform of doublet is
(1) s (2) 1/s (3) 1/s² (4) unity

 69.The steady state part is defined as the response of the system will have a constant value without variations and remains constant at t→ 
(1) ∞  (2) 0  (3) t_r (40 t_s

 70. The damping factor of a system is unity, the system is
(1) over damped (2) under damped (3) critically damped (4) unstable

 71. Which of the following system is stable?
(1)As²+Bs+C =0 (2) As⁴+Bs²+Cs+D=0 (3) –As²+Bs-C=0 (4) As²-Bs-C=0

 72. The first column of Routh table contains the following integers 2,4,-5,3 . The system is
(1) stable (2) unstable (3) Marginally stable (4) absolutely stable

 73. Number of asymptotes in root locus for the above system is
(1) 2 (2) 5 (3) 1 (4) 3

 74. A stable system yields _____ Gain Margin
(1) negative (2) positive (3) zero (4) Infinite

 75. Phase Margin is defined as the value of the difference of the angle corresponding to the gain crossover frequency and
(1) 180⁰ (2) -180⁰ (3) 90⁰ (4) -90⁰

 76. The unit circle of the Nyquist plot transforms into 0 db line of the amplitude plot of the Bode deagram
(1) at 0 frequency (2) at low frequency (3) at high frequency (4) at any frequency

 77. Frequency can be measured by using
(1) Maxwell’s Bridge (2) Schesing Bridge (3) Hay’s Bridge (4) Wien’s Bridge

 78. Maxwell’s bridge is used for measurement of inductance of
(1) low Q coils (2) medium Q colis (3) high Q coils (4) low medium Q coils

 79. Wheatstone bridge widely used for precision measurement of
(1) frequency (2) inductance (3) capacitance (4) resistance

 80. The cheapest inducting instrument among all is
(1) PMMC (2) moving iron (3) Electrodynamometer (4) rectifier

 81.1 mA ammeter has a resistance of 100Ω. It is to be converted to a 1 A ammeter. The value of shunt resistance is
(1) 0.001Ω (2) 0.1001Ω (3) 1,00,000Ω (4) 100Ω

 82.The operating magnetic field in an electrodynamometer type of instrument has a flux density typically about
(1) 1 wb/m² (2) 0.5 wb/m² (3) 0.05 wb/m² (4) 0.005 wb/m²

 83.The type of a system depends on the number of
(1) Poles on s-plane (2) Poles at infinity (3) Poles at origin of s-plane (4) Zeros at infinity

 84.In a single phase induction motor, in order to obtain true value of energy, the shunt magnetic flux should lag behind the applied voltage by
(1) 0⁰ (2) 45⁰ (3) 90⁰ (4) 180⁰

 85.A 53Hz reed type frequency meter is polarized with DC. The new range of frequency meter is
(1) 106 Hz (2) 26.5 Hz (3) 53 Hz (4) 10.6 Hz

 86. Time base generators used in CRO produces -----waveforms
(1) sine (2) square (3) sweep (4) pulse

 87. CRO probe assembly is an application of
(1) multivibrator (2) attenuator (3) clipper (4) clamper

 88. If the damping in a d’assemble galvanometer is only due to electromagnetic effects, the resistance required for critical damping is
(1) G² / √KJ (2) G / √KJ (3) G / 2√KJ (4) G² /  2√KJ

 89. The maximum DC voltage rating ( V_RDC ) of a power diode is useful for selecting---diodes in a DC-DC chopper.
(1) Feedback (2) Free wheeling (3) Series (4) Zener

 90. The terms anode and cathode are not applicable to
(1) SCR (2) Diode (3) Triac (4) GTO

 91. The rectifier-mode operation of Triac an be over come by increasing
(1) anode current (2) gate current (3) holding current (4) latching current

 92. The equivalent capacitance of the depletion layer of reverse biased junction of an SCR is 30pf, fired with a dv / dt of 150 V/μs. The capacitive current (Ic) flowing through the junction is
(1) 4.0 mA (2) 4.5 mA (3) 5.0 mA (4) 5.5 mA

 93.In full- wave rectifier with inductive load, the period for which a thyristor is reverse biased reduces, as the firing angle increases, to
(1) 90⁰ (2) 180⁰ (3) 0⁰ (4) 120⁰

 94. In a half-wave rectifier, voltage source v = 100sin377t, load resistance R = 100Ω and α = 45⁰. The average power in the load is
(1) 12.7 W (2) 22.7W (3) 21.7W (4) 27.1 W

 95.In a single-phase full converter, for continuous conduction each pair of SCR’s conduct for
(1) π – α  (2) π (3) α (4) π + α

 96. A single phase full converter can operate in
(1) 4 quadrants (2) 3 quadrants (3) 2 quadrants (4) 1 quadrant

 97. In DC choppers, per unit ripple is maximum, when duty cycle α is
(1) 0.2 (2) 0.5 (3) 0.7 (4) 0.9

 98. A load commutated chopper circuit has
(1) One thyristor (2) Two thyristors (3) Four thyristor (4) Six thyristor

 99.A 500kW, 3-phase, 3.3kV, 50Hz, 0.8 lag power factor, 4-pole star connected synchronous motor has the Xs = 15Ω, Rs =0, rated field current is 10A. The armature current / Stator current is
(1) 10.93 A (2) 1.093 A (3) 109.3A (4) 0.1093A

 100. The torque expression of synchronous motor has
(1) Two components (2) Three   components (3) Four components (4) five components