Electrical Engineering Smart Series MCQs COMPETITIVE EXAMS SET 12(1100-1218)

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Smart series MCQs set 12 for all electrical engineering tests for the post of Junior Engineer/SDO in WAPDA, GEPCO Jobs NTS, NTDC, MEPCO, IESCO, PESCO, and all competitive exams.

  1. Δ2 V = – P / E is called
    A. Maxwell equation
    B. Poisson equation
    C. Laplace equation
    D. Continuity equation Ans. B
  2. Concept of sending/receiving text etc. on computer networks Is
    A. Online database
    B. Email
    C. Teleconferencing
    D. Tele Printing Ans. B
  3. Drawback of I I R (Infinite impulse response) filters is
    A. Instability

B. Nonlinear
C. Causal
D. All Ans. B

  1. Full-wave rectification needs a minimum number of diodes.
    A. Four
    B. Two
    C. One
    D. Six Ans. B
  2. A circuit of zero lagging power factor behaves as
    A. An inductive circuit
    B. A capacitive circuit
    C. R-L circuit
    D. R-C circuit Ans. A
  3. In order to improve the power factor which device should be connected to the power system
    A. Series capacitor
    B. Shunt capacitor
    C. Series reactor
    D. Shunt reactor Ans. B
  4. In an induction motor when the air gap field between rotor and stator increases power factor of the machine
    A. Increases
    B. Decreases
    C. Does not have any effect
    D. None Ans. B
  5. The power factor of an ac circuit is equal to:
    A. Cosine of the phase angle
    B. Sine of the phase angle
    C. Tangent of the phase angle
    D. Cotangent of the phase angle Ans. A
  6. In an ac circuit, I x sin (Phi) is called the component of the current.
    A. Wattless
    B. Reactive
    C. Quadrature
    D. All the above Ans. D
  7. According to free-electron theory, in metals, electrons revolve because of
    A. Constant V
    B. sinusoidal V
    C. square V
    D. triangular V
    E. Non-periodic V Ans. A
  8. Which of the following is not baseload power plant?
    A. Pump storage
    B. Run water
    C. Diesel
    D. Nuclear Ans. A
  9. The common emitter short circuit current gain is
    A. 0
    B. 1
    C. 10
    D. 100
    Ans. B
  10. By increasing frequency, the current in series resonance circuit before
    A. increase before resonance and decreases after resonance
    B. Decrease before resonance and increase after resonance
    C. Increase before resonance as well increase after resonance
    D. None of the above Ans. A
  11. A steam power generation has an overall efficiency of 20 %. 0.6 Kg of coal is burnt per kWh of electrical energy generated. Calculated the calorific value of fuel?
    A. 7166.67 kCal/kg
    B. 7611.45 kCal/kg
    C. 6921.23 kCal/kg
    D. None of the above Ans. A
  12. The ripple factor of a Half wave rectifier A. 0.5
    B. 1.21
    C. 0.482
    D. 1.11
    Ans. B
  13. In case of photo conductor for Germanium when forbidden energy is 0.72 eV, the critical wavelength for intrinsic excitation will be
    A. 1.73 micro-meter
    B. 1.5 micro-meter
    C. 1.3 micro-meter
    D. 2.73 micro-meter Ans. A
  14. What will be the thermal efficiency of a 240V, 1000W electric kettle if it brings 2 liters of water at 15° C to Boiling point in 15 mins?
    A. 74.56 %
    B. 80.25 %
    C. 79.33 %
    Ans. C
  15. The sequence components of the fault current are as follows: I + = j1.5pU, I – = j0.5 pU, Iz = j pU Which fault is this?
    A. LG fault
    B. LLG fault
    C. LL fault
    D. None of the above Ans. B
  16. An overhead line conductor has an inductance per unit length of L Henry. If the entire medium around the conductor is filled with a dielectric material of permittivity (ϵ), then the inductance will be
    A. L/ ϵ
    B. ϵ/L
    C. 0
    D. Infinite Ans. A
  17. Cosine of the angle which a pole makes with real axis is equal to
    A. Natural frequency
    B. Damping ratio
    C. Peak time
    D. Settling time Ans. D
  18. High ac voltages are mostly measured with
    A. electrostatic voltmeters
    B. potential transformer and voltmeter
    C. current transformer and potential transformer
    D. voltmeter and multiplier Ans. B
  19. Horizontal line in the S plane represents lines of
    A. Damping ratio
    B. Percentage overshoot
    C. constant peak time.
    D. Maximum settling time Ans. C
  20. Types of robotics is done for repetitive jobs
    A. 1
    B. 2
    C. 3
    D. 4

Ans. B

  1. type of robotics is done for Menial task.
    A. 2
    B. 1
    C. 3
    D. 4 Ans. C
  2. In PLC each program line is called
    A. Rung
    B. Step
    C. Line
    D. All Ans. B
  3. In PLC — is replaced by
    A. Motor
    B. Machine
    C. Relay
    D. All Ans. C
  4. As compared to 2-wire DC system the volume of conductor material required in 3-phase 3- wire AC system is
    A. 2/Cos ()
    B. 3 / cos ()
    C. 0.5 / cos 2 ()
    D. 4 / cos () Ans. C
  5. Q-factor is
    A. Directly proportional to resistance of coil
    B. Inversely proportional to resistance of coil
    C. Independent of resistance of coil
    D. None Ans. B
  6. 4 Condensers / Capacitors are connected in parallel with capacitance 4 micro-F, C-eq will be
    A. 16 micro-F
    B. 4 micro-F
    C. 1 micro-F
    D. 1/4 micro-F Ans. A
  7. Current across 90 Ohm resistor is to be reduced by 90% which resistance should be connected in parallel to it
    A. 10-ohms
    B. 900 ohms
    C. 90 ohms

D. 45 ohms Ans. A

  1. Union of two events P(a) and P(b) is P (a U b)
    A. P (a) + P (b) – P (a Π b)
    B. P (a) + P (b)
    C. p (a) + P (b) + P (a Π b)
    D. p (a) + P (b) + P (a U b) Ans. A
  2. Minimum acceptable range of biasing voltage for operational amplifier is – A. – 18 to + 18
    B. -15 to +15
    C. -10 to +10
    D. -5 to +5 Ans. A
  3. In most of the op-amps the level of the roll off is approximately
    A. -3 dB
    B. -6 dB
    C. -12 dB
    D. -18 dB Ans. B
    * -20 dB / decade or -6 dB / octave
  4. In a cumulatively compound DC motor shunt and series field winding
    A. Multiply each other
    B. Subtract each other
    C. Add each other
    D. None Ans. C
  5. DC series motor is known for its
    A. Torque
    B. Speed
    C. Power
    D. None Ans. A
  6. To decrease the power in control system we use
    A. Open loop system
    B. Closed loop system
    C. Open loop and closed loop system
    D. None Ans. A
  7. What is power factor?
    A. True power/apparent power
    B. KW/KVA
    C. R/Z

D. All of the above Ans. D

  1. Generally speaking, a digital multimeter with ammeter, volt meter and ohm meter are used to measure current, voltage and resistance If these 3 are taken on a single unit is called
    A. Low pass filter
    B. High pass filter
    C. Band pass filter
    D. Analog to digital converter
    E. Digital to analog converter Ans. D
  2. In a 3 phase 4 wire AC system the number of voltages we get is
    A. Two
    B. Three
    C. Four
    D. None Ans. A
  3. In an LTI system, if all the poles and zeros are inside the unit circle then
    A. Its inverse does not exist
    B. The system is causal and stable
    C. The inverse of system is causal and stable
    D. Both system and its inverse are causal and stable Ans. D
  4. Z-Transform is used when signal is not
    A. Absolute summable
    B. Squarely summable
    C. Converges
    D. Diverges
    E. A, B, and C Ans. E
  5. In which of the following power plant the availability of power is least reliable
    A. Solar
    B. Wind
    C. Tidal
    D. Geothermal
    E. Biogas Ans. B
  6. is the source which gives constant voltage(V=E) no matter how much current is drawn from it.
    A. Ideal voltage source
    B. Real voltage source
    C. Ideal current source
    D. Ideal resistance source
    E. Real voltage and current source Ans. A

*** NTS marks E as a correct answer

  1. Power in inductive reactance of the circuit is called
    A. Active power
    B. Reactive power
    C. Apparent power
    D. None Ans. B
  2. Ideal transformer has the following properties
    A. Zero winding resistance or no copper loss
    B. Zero core losses
    C. No leakage flux
    D. infinite permeability
    E. All Ans. E
  3. Output variables are known as
    A. Dependent variables
    B. independent variables
    C. constant variables
    D. zero variables Ans. A
  4. Circuit that produces output without external signal source is obtained from
    A. Filter
    B. Amplifier
    C. Oscillator
    D. None Ans. C
  5. Diode limiters are used
    A. To clip positive input cycle
    B. To clip negative input cycle
    C. To add a DC level in input cycle
    D. To clip both positive as well as negative input cycle Ans. D
  6. is used for converting signal from time domain to frequency domain
    A. ROC
    B. Fourier transform
    C. Fourier series
    D. Laplace transform Ans. B
  7. DIAC is a two terminal and layer device.
    A. Two
    B. One
    C. Three

D. Four Ans. D

  1. Load factor is
    A. Average load / peak load
    B. Peak load / average load
    C. Average load / connected load
    D. None Ans. A
  2. Automatic circuit controller or circuit breaker will when a fault occurs in the system.
    A. Open
    B. Close
    C. Trip a sensor alarm
    D. None Ans. A
  3. Superposition theorem is used to solve network.
    A. Thevenin
    B. Norton
    C. Both Norton and Thevenin
    D. Newton Ans. C
  4. Ripple frequency of a bridge rectifier is
    A. same as the input frequency
    B. double the input frequency
    C. half the frequency
    D. None Ans. B
  5. The Norton equivalent of a circuit consists of an ideal in parallel with an ideal impedance or resistor for non-reactive circuits.
    A. Current source
    B. Voltage source
    C. Power source
    D. None Ans. A
  6. Voltage is difference in between two points.
    A. Electric pressure
    B. Magnetic pressure
    C. Pneumatic pressure
    D. Hydraulic pressure Ans. A
  7. Oscilloscope measures
    A. Current
    B. Voltage
    C. Resistance

D. None Ans. B

  1. Which motor gives best variable frequency speed control?
    A. Variable frequency drive
    B. Wound motor
    C. Traction motor
    D. Shunt motor Ans. B
  2. The technology of long-distance communication is known as
    A. Mass communication
    B. Telephony
    C. Telecommunications
    D. Mobile communication Ans. C
  3. The turn on voltage of a Germanium (Ge) junction diode is volts
    A. 0.7
    B. 1.0
    C. 0.1
    D. 0.3
    Ans. D
  4. A tunnel diode
    A. Is a highly doped P-N junction device
    B. Is a gallium arsenide device
    C. Is a point contact diode with a high reverse resistance
    D. Has a small tunnel in its junction Ans. A
  5. FPGA is
    A. Reprogrammable silicon chip
    B. Programmable routing resource
    C. Logic block
    D. High sensitivity silicon chip Ans. A
  6. Which instruction is used to copy a specific word to top of stack in 8056 microprocessors?
    A. Copy
    B. Mov
    C. Push Ans. C
  7. If carrier and modulated signals have frequency of 998KHz and 2KHz respectively, then upper sideband and lower sideband frequencies are
    A. 1000KHz & 998KHz
    B. 998K4z & 900KHz
    C. 1002KHz & 998KHz
    D. 1002KHz & 996KHz Ans. C

*** Actual answer is 996 and 1000. NTS ki pen kis Siri

  1. Brush voltage drop in DC motors is
    A. 20V
    B. 10V
    C. 40V
    D. 2V Ans. D
  2. To decrease the required power of system we prefer
    A. Open loop system
    B. Closed loop system
    C. A combination of both
    D. Open loop system with passive elements Ans. A
  3. For RLC circuit at low frequency, impedance is large because
    A. Xc is larger
    B. XL is large
    C. Xc is smaller
    D. XL is small Ans. A
  4. Natural frequency of a system gives information about
    A. Nature of transient response
    B. Overshoot
    C. Oscillation
    D. Speed of response Ans. D
  5. Armature reaction of an unsaturated DC machine is
    A. Non-magnetizing
    B. Magnetizing
    C. Cross-magnetizing
    D. Demagnetizing Ans. C
  6. What happens if relative speed between rotating flux of stator and rotor of Induction motor is zero?
    A. Torque produced will be very large
    B. Rotor will not run
    C. Rotor will run at a very high speed
    D. Slip will be 5% Ans. B
  7. Fastest possible response without overshoot
    A. Over damped response
    B. Under damped response
    C. Undamped response

D. Critically damped response Ans. D

  1. Hopkinson test on a DC motor is conducted at
    A. No load
    B. Half load
    C. Low load
    D. Full load Ans. D
  2. Usually very wide and sensitive speed control is required in case of
    A. Reciprocating pumps
    B. Colliery winders
    C. Centrifugal blowers
    D. Lathe machine Ans. B
  3. In a parallel resonance circuit at resonance
    A. Impedance is zero
    B. Voltage is maximum
    C. Current is maximum
    D. Impedance is minimum Ans. B
  4. A circuit that produces an output waveform without any external signal source is
    A. Filter
    B. Amplifier
    C. Oscillator
    D. Both A & B Ans. C
  5. In a DC machine maximum losses occur due to
    A. Copper
    B. Iron
    C. Mechanical
    D. Both A & B Ans. A
  6. The test used to determine the efficiency of two transformers at full load is
    A. Open circuit test
    B. Short circuit test
    C. Back-to-back test
    D. Type test Ans. C
  7. Lenz’s law corresponds to the
    A. Law of conservation of momentum
    B. Law of conservation of charge
    C. Law of conservation of emf
    D. Law of conservation of energy

Ans. A

  1. Pointer that cannot be used in register indirect addressing mode is
    A. BX
    B. BP
    C. Si
    D. DI
    E. AX Ans. E
  2. Modulation technique in which carrier is switched between two different carrier levels (0&1) is called
    A. Amplitude shift keying
    B. On-off keying
    C. Frequency modulation
    D. Phase modulation Ans. B
  3. Sign of charge carriers in a conductor can be experimentally found by
    A. Thomson effect
    B. Seebeck effect
    C. Hall effect
    D. Peltier effect Ans. C
  4. Equalizer connections are required for paralleling two
    A. Compound generators
    B. Bipolar generators
    C. Shunt generators
    D. Series generators Ans. A
  5. A DC motor can be identified by
    A. Yoke
    B. Commutator
    C. Size of conductors
    D. Windings Ans. B
  6. The radius of curvature of path of charged particle in a uniform magnetic field is directly proportional to
    A. Flux density of field
    B. Particle’s energy
    C. Particle’s momentum
    D. Particle’s charge Ans. C
  7. Total load transmitted in a 3-phase transmission line is 10,000kW, power factor is 0.8 lagging, I2R losses are 900kW. Then the efficiency of transmission line is
    A. 60%

B. 95%
C. 90%
D. 99%
Ans. C

  1. Which comparison is correct between filament bulb and fluorescent lamp?
    A. Average life fluorescent lamp is 5 to 7 times higher
    B. Fluorescent lamp produces more brightness
    C. Fluorescent lamp produces more sharp shadows
    D. Fluorescent lamp has higher dazzle Ans. A
  2. Crystal frequency of 8051 based system is 16MHz. Period of machine cycle is
    A. 1.333 microseconds
    B. 0.75 microseconds
    C. 0.6 microseconds
    D. 1.66 microseconds Ans. B
  3. A high-speed circuit breaker can complete its operation in
    A. 2 – 3 cycles
    B. 6 – 12 cycles
    C. 3 – 8 cycles
    D. 10 – 12 cycles Ans. C
  4. Force acting on a conductor of length 1m placed at right angles to magnetic field when 1 ampere current flows through it is called
    A. Magnetic force
    B. Electric force
    C. Static force
    D. Lorentz force Ans. A
  5. Oscillator whose frequency can be changed by a variable DC control voltage is
    A. Triangular wave oscillator
    B. Wien bridge oscillator
    C. Crystal oscillator
    D. Voltage control oscillator Ans. D
  6. Inductive circuit time constant is
    A. L/R
    B. R/L
    C. IL/R
    D. I/RL Ans. A
  7. Ash content of Indian coal is mostly
    A. 20%
    B. 5%
    C. 1%
    D. 10%
    Ans. A
  8. A transfer instrument employed in the standardization of a polar type AC potentiometer is
    A. Electrostatic instrument
    B. Dynamometer instrument
    C. Thermal instrument
    D. Moving coil instrument Ans. C
  9. Which of the following can be used to measure a signal of 10 mV at 25MHz?
    A. Vacuum tube voltmeter
    B. Cathode ray oscilloscope
    C. Moving iron voltmeter
    D. Digital multimeter Ans. B
  10. Radio signals are made up of
    A. Voltage and current
    B. Energy
    C. Electrons and protons
    D. Electric and magnetic fields Ans. D
  11. In Petro thermal systems of geothermal energy there is hot dry rock but no underground water exists. In such systems, energy is obtained by
    A. Circulating compressed air
    B. Creating water wells
    C. Pumping water
    D. Both A & B Ans. C
  12. Boiler using lignite as fuels do not use
    A. Travelling grate stoker
    B. Spreader stoker
    C. Underfeed stoker
    D. Both A & B Ans. C
  13. Which meter is suitable for radio frequency measurement?
    A. Electrical resonance frequency meter
    B. Weston frequency meter
    C. Heterodyne frequency meter
    D. Both A & B Ans. C
  14. Overall efficiency of steam locomotive Is dose to
    A. 75 to 80 percent

B. 55 to 60 percent
C. 5 to 10 percent
D. 25 to 30 percent Ans. C

  1. Which of the following is correct?
    A. Only finite number of differential equations can have same integrating factor
    B. Infinitely many differential equations can have the same integrating factor
    C. No two differential equations can have the same integrating factor
    D. No more than two differential equations can have the same integrating factor Ans. B
  2. A substance which can be strongly magnetized is called
    A. Paramagnetic
    B. Diamagnetic
    C. Ferromagnetic
    D. Anti-ferromagnetic Ans. C
  3. Open loop gain of an ideal Op Amp is
    A. Zero
    B. Infinity
    C. Very small
    D. Very high Ans. B
  4. Advantage of an electrodynamometer type instrument is
    A. Low torque/weight ratio
    B. Large operating current
    C. Coil being air cored these instruments are free from hysteresis eddy current losses.
    D. No uniform scale Ans. C
  5. Which of the following instruments are not installed in a substation?
    A. Shunt reactors
    B. Voltage transformers
    C. Exciter
    D. Series capaciter Ans. C
  6. To carry current of 100 rms area of aluminum bus bar must be at least
    A. 25 mm2
    B. 1 mm2
    C. 10 mm2
    D. 50 mm2 Ans. A
  7. Which of the following is true about computer software?
    A. Ordered collection of instructions
    B. Program or set of programs

C. Require no further elaboration
D. All of above Ans. D

  1. Horizontal lines on S plane are lines of
    A. Constant peak time
    B. Constant damping ratio
    C. Constant percent overshoot
    D. Constant settling time Ans. A
  2. In condition no resistor or capacitor is connected from output to its input.
    A. Open loop
    B. Closed loop
    C. Open loop gain
    D. All Ans. A
  3. The cost of generation is/are theoretically minimum if
    A. The system constraints are considered
    B. The operational constraints are considered
    C. Both A and B
    D. The constraints are not considered Ans. D
  4. Under commutation in a DC machine gives rise to
    A. Spark at leading edge of brush
    B. Spark at trailing edge of brush
    C. Spark at middle of brush
    D. No spark at all Ans. B
  5. A tuned circuit has a Q of 100 at its resonant frequency of 500kH bandwidth is
    A. 4kHz
    B. 5kHz
    C. 6kHz
    D. 7KHz Ans. B
  6. What are normal 4 step sequence of a stepper motor if we start to move in clockwise direction with 0110 value?
    A. 1100, 1001, 0011, 0110
    B. 0011, 1001, 1100, 0110
    C. 1001, 1100, 0110, 0011
    D. 0101, 1010, 0101, 1010
    Ans. B
  7. When a single-phase capacitor start induction motor is running at steady speed and delivering a fixed torque then;

A. Forward flux produced by rotor current equals backward flux produced by rotor current
B. Net forward rotating flux equals the net backward rotating flux
C. Peak of forward stator mmf is equal to peak of backward stator mmf
D. Peak of forward rotor mmf is equal to peak of backward rotor mmf Ans. B

  1. Power scale of circle diagram of an induction motor can be found from
    A. Short circuit test only
    B. No load test only
    C. Stator resistance test only
    D. Both A & B Ans. A
  2. Normally Z bus matrix is a
    A. Null matrix
    B. Sparse matrix
    C. Unity matrix
    D. Full matrix Ans. D
  3. If current sensitivity of galvanometer increases voltage sensitivity
    A. Increases
    B. Decreases
    C. Remains unaltered
    D. May increase of decrease Ans. B
  4. Most commonly used single phase energy meters are
    A. Dynamometer type
    B. Electrostatic type
    C. Induction type
    D. Moving coil type Ans. C
  5. Location of poles of system gives info about
    A. Peak time
    B. Percent overshoot
    C. Settling time
    D. All of above Ans. D

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