Electrical EngineeringI Smart Series MCQs COMPETITIVE EXAMS SET 7(601-700)

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Smart series MCQs set 7 for all electrical engineering tests for post of Junior engineer/SDO in WAPDA ,GEPCO jobs NTS, NTDC,MEPCO,IESCO,PESCO and all DESCOS

  1. Which of the following is not a type of thyristor?
    A. DIAC
    B. TRIAC
    C. Light activated
    D. Inverter gate Ans.
  2. Steam pressure can be classified by shaft position, method of drive, and action of steam.
    A. Exhaust pressure
    B. Blade design
    C. Boiler type
    D. Inlet feed to the boilers Ans. A
  3. Strength of magnetic field is increased by
    A. Increasing number of turns
    B. Increasing air gap
    C. Decreasing number of turns
    D. Decreasing air gap Ans A
  4. Skin effect Is proportional to
    A. (Diameter of conductor)2
    B. (Diameter of conductor)4
    C. Diameter of conductor Ans. A
  5. rotor has too weak magnetic field
    A. Salient pole type
    B. Non-Salient pole type
    C. Both A and B
    D. None Ans. A
  6. Which of following is not a type of transformer?
    A. Resonant transformer
    B. laminated transformer
    C. Single Instrument transformer
    D. Ferrite core transformer
    E. Cast iron transformer Ans. E
  7. Which of the following is semi controlled power switch?
    A. Thyristor

B. Transistor
C. Diode
D. All Ans, A

  1. Stator core ls made of any thin metal plates or sheets joined together called ꞏ
    A. Wallet
    B. Slots
    C. laminations
    D. Pastes Ans. C
  2. In substation is a substation without a transformer where there is no step up or step- down voltage transformation and operating at only a single voltage level.
    A. Switching
    B. Collector
    C. Converter
    D. None of above Ans. A
  3. A transfers power from transmission system to distribution system of an area. It is uneconomical to directly connect electricity consumers to the main transmission network, unless they use large, amounts of power
    A. Distribution substation
    B. Transmission substation
    C. Generating substation
    D. None Ans. A
  4. In air blast circuit breaker, the pressure of air is of the order of
    A. 3 to 5 kg/cm
    B. 20 to 30kg/cm
    C. 30 to 50 kg/cm
    D. None Ans. B
  5. In induction motor when the length of the air gap is increased, the magnetizing current of the motor increases while the short circuit current
    A. Decreased
    B. Increased
    C. Remains unchanged
    D. Grows exponentially Ans. C
  6. In DC choppers per unit ripple is maximum when duty cycle alpha (a) is A. 0.1
    B. B 0.3

C. 0.5
D. 0.7
Ans. C

  1. In control systems with increases feedback
    A. System stability and system gain decreases
    B. System stability decreases and system gain increases
    C. System stability decreases and system gain decreases
    D. System stability as well as gain increases Ans. A
  2. The electrostatic potential inside a hollow conductor is
    A. Constant
    B. Minimum
    C. Maximum
    D. Zero Ans. A
  3. Inside a hollow spherical conductor electric field is
    A. Constant
    B. Minimum
    C. Maximum
    D. Zero Ans. D
  4. In an FM signal, the power
    A. Increases as the modulation index increases
    B. Reduces as the modulation index increases
    C. Reduces as the modulation index decreases
    D. Remains constant when modulation index increases Ans. D
  5. Microprocessor at most elemental level is made of
    A. Transistors
    B. Flip flops
    C. Digital logic gates & latches Ans C
  6. 16-bit binary word provides approximately how many combinations?
    A. 2n code combinations
    B. 256 codes combinations
    C. 65000
    D. 0001.10
    Ans. C
  7. S2 – 4RT > 0 is type of wave equation.
    A. Elliptic
    B. Parabolic
    C. Hyperbolic
    D. Semi-circle Ans. C
  8. S2 – 4 RT = 0 is type of wave equation.
    A. Elliptic
    B. Parabolic
    C. Hyperbolic
    D. Semi-circle Ans. B
  9. S2 – 4 RT < 0 is type of wave equation.
    A. Elliptic
    B. Parabolic
    C. Hyperbolic
    D. Semi-circle Ans. A
  10. let y = x2 + 1, then the average rate of change of ‘ y’ with respect to ‘ x’ over interval (3, 5) is
    A. -8
    B. 2x
    C. 8
    D. 16 Ans. B
  11. A 5 feet ladder leg against the wall slips in such a way that its base is moving away from the wall at the rate of 2 feet/sec. At that instant when base is 4 feet from the wall. How fast is top of the ladder moving down the wall of that instant?
    A. 2 ft/sec
    B. -4 ft/sec
    C. -8 ft/sec
    D. -8/3 ft/sec Ans. D
  12. If a large number of gate inputs are connected in a TTL circuit, what will happen to Voh and Voh-min?
    A. Voh and Voh-min are unaffected
    B. Voh exceeds V ohn
    C. Voh-min drops be milow Voh
    D. Voh chops below Voh-min Ans. D
  13. The execution unit has a 16-bit architectural unit (ALU). Which of the following has not been performed by ALU?
    A. AND
    B. OR
    C. XOR

D. NAND Ans. D

  1. A signal is defined as power signal if and only if
    A. Its power is normalized by assuming R to be 1 ohm
    B. Power is de-normalized of normal value
    C. It has infinite energy but non zero power 0 < P < infinity for all time
    D. It is periodic Ans. C
  2. Purpose of a transfer function is to decide.
    A. System is FIFO
    B. System is not stable
    C. System is stable BIBO
    D. None Ans. C
  3. Efficiency of electric motors is usually between A. 80 – 90%
    B. 70 – 80%
    C. 75-98%
    D. 60 – 98%
    Ans. A
  4. The Primary and secondary induced EMFs (El and E2) in a two winding transformer are always
    A. Equal in magnitude
    B. Anti-phase with each other
    C. In phase with each other
    D. Determined by load on transformer Ans. C
  5. The main difference between electric lines and magnetic lines of force
    A. Electric lines are closed curves whereas magnetic lines of force are not
    B. Electric lines are in the form of open curves whereas the magnetic linen are closed curves
    C. Electric lines tend to contract lengthwise whereas magnetic lines do not
    D. None Ans. B
  6. In synchronous motor if load (same) is off suddenly then motor
    A. Begins to speed up
    B. Begins to slow
    C. Suddenly have to carry load
    D. Remains working Ans. A
  7. A shunt generator delivers 195 A at a terminal potential is 270V. The armature resistances are
    0.02 0 and 50 0 respectively. What is the value of generated EMF?
    A. 246V

B. 28V
C. 254V
D. 2V Ans. C

  1. A 220 V shunt motor takes a total current of 80A and runs at 800RPM. Resistance of shunt field is 50 ohms and that of armature is 0.1 ohms. Iron and friction losses amount to 1600 W. What is driving power of motor?
    A. 16050 W
    B. 14500 W
    C. 12600 W
    D. 18500 W
    Ans A
  2. wave is a high frequency waveform (sinusoidal usually) that is modulated with an input signal.
    A. Modulated
    B. Carrier
    C. Sinusoidal
    D. Amplitude Ans. B
  3. What principle is used by indicating instruments?
    A. Electromagnet principle
    B. Gravity and spring
    C. Lenz law
    D. None of above Ans. B
  4. Power Carrying capability of system is limited by
    A. Thermal conditions
    B. Design of system
    C. None of above Ans. A
  5. A transformer has negative voltage regulation when its load power factor
    A. Zero
    B. Unity
    C. Leading
    D. Lagging Ans C
  6. The commercial efficiency of a transformer while on open circuit is
    A. Zero
    B. Maximum
    C. Either zero or 100%
    D. 100%
    Ans. A
  7. In large power transformer, best utilization of available core space can be made by employing cross section.
    A. Rectangular
    B. Square
    C. Stepped
    D. None of above Ans. C
  8. Arrangement of data in a specific order is called
    A. Merging
    B. Sorting
    C. Classification
    D. Verification Ans. B
  9. When covalent bonds break
    A. Holes and electrons pair are produced
    B. Ions are created
    C. Both A & B
    D. None of above
    Ans. A
  10. The duration of the pulse in a pulse triggering system for SCRs should at least
    A. 60 micro seconds
    B. 40 micro seconds
    C. 20 micro seconds
    D. 10 micro seconds
    Ans. D
  11. IBM 360 series was introduced in 642
    A. First generation
    B. second generation
    C. Third generation
    D. 1950
    Ans. C
  12. The power factor of ac circuit lies between
    A. 0 and 1
    B. -1 and 1
    C. 0 and -1
    D. None of above Ans. A
  13. The heat developed in an electric iron is attributed to power
    A. Apparent
    B. Reactive
    C. True
    D. True and reactive Ans. C
  14. When the power factor in the transmission line is leading, which device is employed at substation to reduce the power factor?
    A. CVT
    B. Shunt Reactor
    C. Synchronous condenser
    D. None of above Ans. B
  15. In a circuit, low reactive power compared to true power indicates
    A. Low power factor
    B. High power factor
    C. Low efficiency
    D. High efficiency Ans. B
  16. The rating of given on the name plate of a transformer indicates the
    A. True power which it can supply
    B. Apparent power which it can supply
    C. Apparent power which it draws from the supply mains
    D. True power which it draws from the supply mains Ans. B
  17. In a stepper motor the speed of rotation is determined by
    A. Frequency of the waveform
    B. Input Current
    C. Voltage applied to the motor
    D. All of these Ans. A
  18. Electrical field Intensity on equipotential surface is
    A. Parallel to surface
    B. Adjacent to surface
    C. Alongside the surface
    D. Perpendicular to surface Ans. D
  19. Mechanical energy is supplied to a DC generator at the rate of 4200 J/s. The generator delivers 32.2 Amp at 120 V. How much energy is cost per minute of operation?
    A. 20060 J
    B. 20160 J
    C. 23060 J
    D. 25060 J
    Ans. B
  20. Norton equivalent current is
    A. An open circuit
    B. A pure resistive circuit
    C. Short circuit through load
    D. None of above

Ans. C

  1. The main current crossing the collector junction in a normally biased NPN transistor is
    A. Diffusion current
    B. Base current
    C. Equal current
    D. Drift current Ans. D
  2. The only place where slip ring induction motors used in thermal power plants is
    A. Boilers
    B. Coal handling plant
    C. Not used in thermal plants
    D. None of above Ans. B
  3. An input transducer
    A. Converts voltage to current
    B. Converts current to voltage
    C. Converts electrical quantity to non-electrical
    D. Non electrical quantity to electrical quantity Ans. D
  4. Low attenuation rate and bandwidth is the cause of use of optical fiber system for communication.
    A. Low
    B. Narrow
    C. High
    D. Constant Ans. C
  5. peak time is constant along
    A. Imaginary axis
    B. Diagonal
    C. Real axis
    D. None of above Ans. C
  6. A voltmeter using thermocouple measures
    A. Peak value
    B. RMS value
    C. Average value
    D. Peak to peak value Ans. B
  7. Which coal will have highest ash content?
    A. Bituminous coal
    B. Grade 1 steam coal
    C. Coking coal

D. Lignite Ans. D

  1. What is the main disadvantage of phase advancers?
    A. Cannot be used for motors below 200 H.P
    B. Produces noise
    C. Can be used where synchronous motors is inadmissible
    D. None of these Ans. A
  2. Under what condition is D.C supply applied safely to the primary of a transformer?
    A. We can connect directly to DC; no condition is required
    B. We cannot connect to DC supply
    C. High resistance should be connected in series with primary, but circuit will be useless
    D. Above statements are wrong Ans. C
  3. In a Transformer, the primary flux is always the secondary flux.
    A. Greater
    B. Smaller
    C. Twice
    D. Equal Ans. D
  4. Bandwidth can be increased by use of network.
    A. Phase lag
    B. Phase lead
    C. None
    D. Mesh Ans. B
  5. Which of the following is the source of non-linearity?
    A. Backlash in gear
    B. Saturation in effective is amplified
    C. Threshold season
    D. All of above Ans. D
  6. The program for early PLC was in
    A. Boolean algebra
    B. Ladder logic
    C. Arithmetic logic
    D. All of above Ans. B
  7. The pointer which cannot he used in the register indirect addressing mode
    A. BX
    B. BP
    C. SI
    D. DI

E. AX Ans. E

  1. compensation is used to decrease steady state error.
    A. Lag
    B. Lead
    C. Lead and lag
    D. Lag and lead
    E. None of above Ans. A
  2. The mutual inductance between two coils is zero when the fluxes produced by them
    A. Aid each other
    B. Oppose each other
    C. Are at right angle to each other
    D. None of above Ans. C
  3. If the admittance of a parallel AC circuit is increased, the circuit currents
    A. Decreased
    B. Increased
    C. Remains constant
    D. None Ans. B
  4. Impedance is for AC circuit and resistance is for DC circuit, the difference is because of
    A. AC is vector while DC is scalar
    B. AC changes its direction quantity while DC does not
    C. Voltage phasor or current phasor
    D. None of above Ans. C
  5. 40 W, 60 W, 100 W and 200 W bulbs are connected in series which bulb will glow brighter?

A. 40 W
B. 60 W
C. 100 W
D. 200 W Ans. A

  1. Which of the following is true?
    A. Transducer and actuator are sensor
    B. Sensor and actuator are transducer
    C. Sensor and transducer are actuator
    D. None Ans. B
  2. Peak to peak 200 Volt will be read by an AC voltmeter as
    A. 141.7 V
    B. 100 V

C. 200 V
D. 70.7 V
Ans. D

  1. The square law of photo detector gives current. This current is proportional to of combined optical field.
    A. Square
    B. Cube
    C. Square root
    D. None of above Ans. A
  2. Intensity of light depends on
    A. Wavelength
    B. Frequency
    C. Velocity
    D. Amplitude
    Ans. D
  3. The is an electromagnetic carrier wave which is modulated to carry information.
    A. Air
    B. Sound
    C. Light
    D. Electricity Ans. C
  4. A super conductor may be used for generating
    A. Voltage
    B. Current
    C. Pressure
    D. Magnetic field Ans. D
  5. Materials in superconducting state have the property of
    A. Absorbing magnetic field
    B. Repelling magnetic field
    C. Absorbing electric field
    D. Repelling electric field Ans. B
  6. Stability of LC tuned circuit depends on
    A. Quality factor
    B. Inductor
    C. Capacitor
    D. None of above Ans. A
  7. Primary and secondary winding of an ordinary 2-winding transformer always has
    A. Different number of turns
    B. Same size of copper wire

C. A common magnetic
D. Separate magnetic circuit Ans. C

  1. In a transformer, the leakage flux of each winding is proportional to the current in that winding because
    A. Ohm’s law applied to magnetic circuits
    B. Leakage paths do not saturate
    C. The two windings are electrically isolated
    D. Magnetic flux is confined to core Ans. B
  2. Common emitter is used for amplification of
    A. Current
    B. Voltage
    C. Power
    D. All Ans. C
  3. Transformer is rated as KVA instead of KW because
    A. Load power factor is unknown
    B. Transformer loss depends on volt-amperes
    C. It has become customary
    D. All of above Ans. B
  4. Reverse bias of JFET increases its width of depletion layer and
    A. Decrease its channel capacitance
    B. Increase its channel capacitance
    C. Decrease its channel resistance
    D. Increase its channel resistance Ans. D
  5. Net reactance in RLC at resonance is
    A. Maximum
    B. Minimum
    C. Zero
    D. Infinity Ans. B
  6. Circuit current is in series RLC at resonance.
    A. Maximum
    B. Minimum
    C. Zero
    D. Infinity Ans. A
  7. is current in transistor due to minority charge carriers.
    A. Forward leakage current
    B. Reverse leakage current
    C. Forward resistance of transistor

D. Reverse resistance of transistor Ans. B

  1. Which configuration can be used to convert high impedance into low impedance by using OP-AMP?
    A. Inverting
    B. Non-inverting
    C. Summing amplifier
    D. Voltage follower Ans. D
  2. The CMRR should be for better noise cancellation in OP-AMP.
    A. Low
    B. Zero
    C. High
    D. None of above Ans. C
  3. The VI characteristics of UJT is
    A. Similar to CE with a linear and saturation region
    B. Similar to tunnel diode in some respects
    C. Similar to FET with a linear and pinch-off region
    D. Similar to PN junction in some respects Ans. B
  4. A DC-DC converter with a high step-up voltage gain is used for many applications such as
    A. High intensity discharge lamp ballasts for automobile headlamps
    B. Fuel energy conversion system
    C. Solar cell energy conversion system
    D. Battery backup systems
    E. All Ans. E
  5. Transfer function is
    A. Mathematical model
    B. System with no physical structure
    C. System with no defined inputs
    D. Can be calculated through differential equations
    E. All Ans. E
  6. Which system needs more stability?
    A. Automatic washing machine
    B. Traffic signal system
    C. Home heating system
    D. Motor with position control
    E. Remote control Ans. D
  7. In parallel resonance RLC circuit

A. Impedance is minimum
B. Power factor is unity
C. Current is maximum
D. None of above Ans. B

  1. Cross over distortion is maximum in amplifier.
    A. Class A
    B. Class B
    C. Class H
    D. Class C
    E. Class AB Ans. B
  2. is maximum when RLC circuit is in resonance.
    A. Inductive current
    B. Power dissipation
    C. Capacitive voltage
    D. None Ans B
  3. Group diversity factor is
    A. Less than 1
    B. Greater than 1
    C. Zero
    D. Equal to 1 Ans. B
  4. Like 3 phases gives constant power transfer to the linear load.
    A. HVDC
    B. Spilt phase
    C. Two phases
    D. Single phase Ans. C
  5. Which of the following technique/method is-used for the measurements of ac high frequency voltages?
    A. Peak voltmeter
    B. Series resistance micro ammeter
    C. Resistance potential divider
    D. Any of above Ans. A

Electrical EngineeringI Smart Series MCQs COMPETITIVE EXAMS SET 8(701-800)

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