Electrical EngineeringI Smart Series MCQs COMPETITIVE EXAMS SET 9(801-900)

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Smart series MCQs set 9 for all electrical engineering tests for post of Junior engineer/SDO in WAPDA ,GEPCO jobs NTS, NTDC,MEPCO,IESCO,PESCO and all DESCOS

  1. Voltage regulators normally use
    A. Negative feedback
    B. Positive feedback
    C. No feedback
    D. Phase limiting Ans. A
  2. A power supply with low output impedance has low
    A. Load regulation
    B. Current limiting
    C. Line regulation
    D. Efficiency Ans. A
  3. When electrical and mechanical degrees become same in DC machine
    A. Speed more than 360 rpm
    B. Less than 360 rpm
    C. In 4 pole machines
    D. In 2 pole machines Ans. D
  4. In which braking method of induction motor, the motor stops dissipating heat in the resistor
    A. Regenerative braking
    B. Dynamic braking
    C. Plugging
    D. All of above Ans. B
  5. In AC systems, ground or earth is connected to
    A. Neutral
    B. One of the phases
    C. Midpoint
    D. None Ans. A
  6. Bus bar is at
    A. Constant voltage
    B. Constant current
    C. Both A & B
    D. None of above
    E. Variable voltage and current Ans. A
  7. For which of following loads voltage drop is minimum
    A. Load at the end of feeder
    B. Uniformly distributed load
    C. Uniformly increasing load
    D. Uniformly decreasing load Ans. D
  8. In a DC machine, hysteresis loss is
    A. Proportional to frequency
    B. Inversely proportional to frequency
    C. Proportional to square of frequency
    D. None of above Ans. A
  9. In a DC machine, eddy current loss is
    A. Proportional to frequency
    B. Inversely proportional to frequency
    C. Proportional to square of frequency
    D. None of above Ans C
  10. The Common Collector configuration is used for
    A. Impedance matching
    B. Voltage gain
    C. High power applications
    D. None of above Ans. A
  11. The current in a copper wire is because of
    A. Free electrons
    B. Holes
    C. Holes and free electrons
    D. Ions Ans. A
  12. DC transmission is economical for
    A. Short transmission lines
    B. Medium transmission lines
    C. Long transmission lines
    D. Both medium and long transmission lines Ans. C
  13. When the receiving end voltage is greater than the sending end voltage this is called
    A. Skin effect
    B. Proximity effect
    C. Corona effect
    D. Ferranti effect Ans. D
  14. In modern computers which of the following technology is used now a days.
    A. MOSFET
    B. BJT
    C. JFET
    D. TTL Ans. D
  15. In domestic wiring earth is provided to
    A. Protect human beings from electric shock
    B. To protect machines
    C. To protect human and machines
    D. To protect birds Ans. A
  16. Fuse wire is installed
    A. In series with the wire circuit
    B. In series with the neutral wire
    C. In parallel with the neutral wire
    D. In parallel with earth wire in the circuit Ans. A
  17. The merging of a free electron and a hole is called
    A. Covalent bonding
    B. Lifetime
    C. Recombination
    D. Thermal energy Ans. C
  18. In an intrinsic semiconductor, the number of free electrons
    A. Equals the number of holes
    B. Is greater than the number of holes
    C. Is less than the number of holes
    D. None of above Ans. A
  19. At absolute zero temperature (-273 10 C) an intrinsic semiconductor has
    A. Few free electrons
    B. Many holes
    C. many free electrons
    D. No holes or free electrons Ans. D
  20. When the graph of current versus voltage is a straight line, the device is referred to as
    A. Active
    B. Linear
    C. Non linear
    D. Passive Ans. B
  21. Meggar test is used to measure
    A. To measure the insulation resistance
    B. To check the calibration of instrument
    C. To find the unknown resistance
    D. None of above Ans. A
  22. Transformer oil is used for
    A. Insulation
    B. Cooling
    C. Both A & B
    D. Lubrication Ans. C
  23. Which circuit breakers are normally used for 11 KV?
    A. Oil circuit breaker
    B. SF6
    C. Vacuum circuit breaker
    D. Air blast circuit breaker Ans. C
  24. Trans conductance indicates how effectively the input voltage controls the
    A. Voltage gain
    B. Input resistance
    C. Supply voltage
    D. Output voltage Ans. D
  25. Demand factor is the ratio of
    A. Maximum demand to connected load
    B. Connected load to maximum demand
    C. Maximum demand to average load
    D. Average load to maximum load Ans. A
  26. An Over excited synchronous generator supplies to the grid
    A. Active power
    B. Reactive power
    C. Active load
    D. Reactive load Ans. B
  27. The amount of heat necessary to raise the temperature of one kg (or 1 liter) of pure water by 1 Celsius degree at normal atmospheric pressure is called
    A. 1 calorie
    B. Kcal
    C. Joule
    D. None of above Ans. B
  28. Power FETs are
    A. Integrated circuits
    B. Small signal devices
    C. Used mostly with analog signals
    D. Used to switch large currents Ans. D
  29. Most power FETS are
    A. Used in high current applications
    B. Digital computers
    C. RF stages
    D. Integrated circuits Ans. A
  30. Monolithic ICs are
    A. Forms of discrete circuits
    B. On a single chip
    C. Combinations of thin film and thick film circuits
    D. Also called hybrid ICs Ans. B
  31. For ceiling fans generally, the single-phase motor used is
    A. Split phase type
    B. Capacitor start type
    C. Capacitor start and run type
    D. Permanent capacitor type Ans. D
  32. The gain of two cascaded amplifiers is
    A. Added
    B. Subtracted
    C. Multiplied
    D. Divided Ans. C
  33. Kirchhoff s second law is based on the law of conservation of
    A. Charge
    B. Energy
    C. Momentum
    D. Mass Ans. B
  34. Which of the following is not the same as watt?
    A. Joule/sec
    B. Amperes/volt
    C. Amperes x volts
    D. (amperes)2 x ohm Ans. B
  35. Which method can be used for absolute measurement of resistances?
    A. Ohm’s law method

B. Whetstone bridge method
C. Releigh method
D. Lortentz method Ans. B

  1. A standard 60W bulb is in series with a room heater and connected across the mains. If 60W bulb is replaced by 100W bulb
    A. The heater output will increase
    B. The heater output will reduce
    C. The heater output remains unaltered
    D. None of above Ans. A
  2. Which material is expected to have least resistivity?
    A. Copper
    B. Lead
    C. Mercury
    D. Zinc Ans. A
  3. Certain substances lose their electrical resistance completely at finite low temperatures. Such substances are called
    A. Dielectrics
    B. Super conductors
    C. Semi-conductors
    D. Perfect conductors Ans. B
  4. The plates of a lead acid battery are made of
    A. Rolled zinc-copper alloy
    B. Cast antimonial lead alloy
    C. Perforated nickel cadmium alloy
    D. Pressed antimony bismuth alloy Ans. B
  5. In a lead acid battery, during charging
    A. Anode becomes whitish in color
    B. Voltage drops
    C. Specific gravity of acid increases
    D. The cell gives out energy Ans. C
  6. The value of specific gravity of acid when a lead acid battery is fully charged is A. 1.285
    B. 2.185
    C. 2.585
    D. 2.9585
    Ans. A
  7. The indication of the state of charge of a battery is best given by

A. Specific gravity of electrolyte
B. Temperature of electrolyte
C. Color of electrolyte
D. Level of electrolyte Ans. A

  1. On watt hour basis the efficiency of a lead acid battery is in the range
    A. 90 to 95 percent
    B. 80 to 85 percent
    C. 70 to 85 percent
    D. 60 to 70 percent Ans. C
  2. The internal resistance of a dry cell is of the order of
    A. 0.2 to 0.4 ohm
    B. 1 to 1.5 ohm
    C. 2 to 5 ohms
    D. 1 to 15 ohms Ans. A
  3. The electrode for a battery must be
    A. A good conductor of electricity
    B. A bad conductor of electricity
    C. A semi-conductor
    D. An insulator Ans A
  4. The specific gravity of acid is checked with the help of a
    A. Hygrometer
    B. Lactometer
    C. Hydrometer
    D. Cell tester Ans. C
  5. Cells are connected in series to
    A. Increase the voltage output
    B. Decrease the Voltage output
    C. decrease the internal resistance
    D. Increase the current capacity Ans. A
  6. A battery whose EMF is 45 volts is connected to a 20-ohm resistance and current of 2.1A flows. The terminal voltage is
    A. 42V
    B. 45V
    C. 40V
    D. 54V Ans. A
  7. The best instrument for the measurement of EMF of a cell is

A. Voltmeter
B. Ammeter
C. Potentiometer
D. Wheatstone bridge Ans. C

  1. The RMS value of sinusoidal 200V peak to peak wave is
    A. 200V
    B. 100/ sqrt (2) V
    C. 200/ sqrt (2) V
    D. 100V Ans. B
  2. Which wave has the highest value of form factor?
    A. Sine wave
    B. Triangular wave
    C. Square wave
    D. Half wave rectified sine wave Ans. D
  3. The form factor of DC supply voltage is always
    A. Zero
    B. 0.5
    C. Unity
    D. Infinite Ans. C
  4. Which of the following relation is incorrect? Power factor=
    A. Real power / Apparent power
    B. kW/kVA
    C. Resistance / Impedance
    D. Conductance / Susceptance Ans. D
  5. The capacitors for power factor correction are rated in terms of
    A. Voltage
    B. VA
    C. KW
    D. KVAR Ans. D
  6. Power factor of an Inductive circuit can be improved by connecting capacitor to it in
    A. Series
    B. parallel
    C. Depends on value of C
    D. Either series or parallel Ans. B
  7. A series circuit consisting of R=1.2 k ohms and C= 0.4 micro-F is supplied with 45 V at a frequency of 1kHz. The reactive power will be

A. 0.1 VAR
B. 0.4 VAR
C. 0.81 VAR
D. 1.62 VAR Ans. C

  1. A non-linear network does not satisfy
    A. Homogeneity condition
    B. Super position condition
    C. Both A & B
    D. None of above Ans. C
  2. A coil with 1000 turns carrying a current of 8A produces a flux of 6 x 10-6 Wb. The inductance of coil would be
    A. 0.75 H
    B. 0.075 H
    C. 0.0075 H
    D. 0.00075 H
    Ans. D
  3. The super position theorem is applicable to
    A. Linear responses only
    B. Linear and non-linear responses only
    C. Linear, non-linear and time variant responses
    D. None of above Ans. A
  4. The super position theorem is applicable to
    A. Current only
    B. Voltage only
    C. Both current and voltage
    D. Current, voltage and power Ans. D
  5. A unit ramp function when integrated yields
    A. Unit parabolic function
    B. Unit ramp function
    C. Unit doublet
    D. Unit impulse function Ans A
  6. The system with characteristic equation s4 +3s3 + 6s2+ 9s+12= 0
    A. Stable
    B. Unstable
    C. Marginality stable
    D. None Ans. B
  7. If a zero appears in first column of the Routh table, the system is
    A. Necessarily stable
    B. Necessarily unstable
    C. Marginally stable
    D. None Ans. B
  8. The open loop transfer functions of systems are given below. Identify the system that is not stable for all values of gain constant K

Ans. D

  1. The main application of transfer function is in the study of
    A. Steady behaviors of system
    B. Steady as well as transient behaviors of systems
    C. Only transient behaviors of system
    D. Neither steady nor transient behaviors of system Ans. B
  2. Which signal will become zero when the feedback-signal and reference signs are equal?
    A. Actuating signal
    B. Reference signal
    C. Feedback signal
    D. Input signal Ans. A
  3. The output of a thermocouple is
    A. DC current
    B. AC current
    C. DC voltage
    D. AC voltage Ans. C
  4. The Bode plot is used to analyze
    A. All phase network
    B. Lag lead network
    C. Minimum phase network
    D. Maximum phase network Ans. C
  5. Non linearity caused by servo motor is
    A. Saturation
    B. Backlash
    C. Static friction

D. None of above Ans. A

  1. Resistivity of metals is expressed in terms of
    A. micro-ohm
    B. Micro ohm/cm
    C. Micro ohm-cm2
    D. micro-ohm-cm Ans. D
  2. Constantan contains
    A. Copper and nickel
    B. Copper and tungsten
    C. Tungsten and silver
    D. Silver and tin Ans. A
  3. Bakelite is
    A. A semiconductor
    B. Incombustible
    C. Low resistance conductor
    D. Highly inflammable Ans. B
  4. Dielectric constant for vacuum is
    A. Infinity
    B. 100
    C. 1
    D. Zero Ans. C
  5. Which material can be used at temperatures above 100?
    A. Polythene
    B. Teflon
    C. Rubber
    D. Paraffin wax Ans. B
  6. A force of 1 Newton is experienced between 2 equal charges in space, separated by 1m and having a magnitude of
    A. 1 coulomb
    B. 10 micro-coulombs
    C. 100 pico-coulombs
    D. None of above Ans. B
  7. Which medium has least dielectric strength?
    A. Air
    B. Quartz
    C. Glass

D. Paraffin wax Ans. A

  1. A region around a stationary electric charge has
    A. Magnetic field
    B. Electric field
    C. Both magnetic and electric field
    D. Neither magnetic nor electric field Ans. B
  2. One volt is same as
    A. One joule
    B. One joule/sec
    C. One joule/coulomb
    D. One coulomb/joule Ans. C
  3. One farad is the same as
    A. One coulomb/volt
    B. One joule/ volt
    C. One joule/coulomb
    D. One coulomb/joule Ans. A
  4. Two infinitely long parallel conductors in vacuum are separated by a distance of 1 meter between centers, when a current of 1 ampere flows through each conductor. The magnitude of force exerted by the two conductors on each other will be
    A. 2 x 10-7 N per meter length
    B. 2 x 10-5 N per meter length
    C. 2 x 10-3 N per meter length
    D. 2 x 10-2 N per meter length Ans. A
  5. A device that converts from decimal to binary number is called
    A. Decoder
    B. Encoder
    C. CPU
    D. Converter Ans. B
  6. The hexadecimal number 86C7 is equivalent to decimal number A. 49761
    B. 46791
    C. 47691
    D. 49761
    Ans. B
  7. Monolithic technology is widely used in the manufacture of
    A. Antenna
    B. Transistors

C. Integrated circuits
D. All of above Ans. C

  1. 64K is
    A.6400
    B.64000
    C.65536
    D.66536
    Ans: C
  2. Microprocessor 8085 is the enhanced version of the with essentiality same construction set.
    A. 6800
    B. 68000
    C. 8080
    D. 8000
    Ans. C
  3. Opcode
    A. That part of construction which tells the computer what operation to perform
    B. An auxiliary register that stores the data to be added or subtracted from the accumulator
    C. The register that receives the constructions from the memory
    D. One of the constructions in the memory set Ans. A
  4. In 8085, the instruction register is part of the control unit. The contents of the instruction register are split into two nibbles. The upper nib goes to the
    A. Memory address
    B. Controller sequence
    C. Micro-instruction
    D. Source program Ans. B
  5. Interaction between a CPU and a peripheral device that takes place during an I/O operation is known as
    A. Handshaking
    B. Flagging
    C. Relocating
    D. Subroutine Ans. A
  6. Equalizer rings are required in a lap winding DC machine
    A. To decrease armature reaction
    B. To improve commutation
    C. To filter out harmonics
    D. To prevent flow of circulating currents through the brushes Ans. D
  7. If the no load voltage of a certain generator is 220 V and the rated voltage is 200 V, then the voltage regulation is
    A. 1%
    B. 10%
    C. 20%
    D. 9% Ans. B
  8. The critical resistance of DC generator refers to the resistance of
    A. Armature
    B. Load
    C. Field
    D. Brushes Ans. A
  9. The armature reaction of an unsaturated DC machine is
    A. Non-magnetizing
    B. Magnetizing
    C. Demagnetizing
    D. Cross-magnetizing Ans. D
  10. The speed of a series-wound DC motor
    A. Can be controlled by shunt field regulator
    B. Cannot be controlled by diverter
    C. Increases as flux decreases
    D. Increases as armature circuit resistance increases Ans. C
  11. The function of breather in a transformer is
    A. To provide oxygen to the cooling oil
    B. To provide cooling air
    C. To arrest flow of moisture when outside air enters the transformer
    D. To filter the transformer oil Ans. C
  12. Power transformers are usually designed to have maximum efficiency at
    A. Near full load
    B. At 75% of full load
    C. At 50% of full load
    D. Between 50% and 75% of full load Ans. A
  13. Distribution transformers are usually designed to have Maximum efficiency at
    A. Near full load
    B. Near 75% of full load
    C. Near 50% of full load
    D. Near no load Ans. C
  14. Which value of flux is involved in the emf equation of transformer?
    A. Maximum value
    B. Average value
    C. RMS value
    D. Critical value Ans. A
  15. An alternator is said to be over excited when it is operating at
    A. Unity power factor
    B. Leading power factor
    C. Lagging power factor
    D. Lagging to leading power factor Ans. C
    E.
  16. For an alternator when the power factor of load is unity
    A. The armature flux will have square waveform
    B. The armature flux will be de magnetizing
    C. The armature flux will be cross magnetizing
    D. The armature flux will reduce to zero Ans. C
  17. Which of the following is likely to be the full load power factor of a three-phase induction motor?
    A. 0.2 leading
    B. 0.2 lagging
    C. 0.8 lagging
    D. 0.8 leading Ans. C
  18. Which single phase motor has relatively high-power factor?
    A. Universal motor
    B. Split phase motor
    C. Repulsion motor
    D. Synchronous motor Ans. A

Electrical EngineeringI Smart Series MCQs COMPETITIVE EXAMS SET 10(901-1000)

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