Railways General Science & Technology Alternating Current / प्रत्यावर्ती धारा Sample Paper

done Alternating Current and Electromagnetic Induction Sample Test Paper-10 Total Questions - 20    [Download]

• question_answer1)
  A transformer is employed to
  A)
   Convert A.C. into D.C.
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  B)
   Convert D.C. into A.C.
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  C)
   Obtain a suitable A.C. voltage
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  D)
   Obtain a suitable D.C. voltage
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• question_answer2)
  To convert mechanical energy into electrical energy, one can use
  A)
   DC dynamo     
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  B)
   AC dynamo
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  C)
   Motor  
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  D)
   [a] & [b]
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• question_answer3)
  The phenomenon of electromagnetic induction is
  A)
   The process of charging a body.
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  B)
   The process of generating magnetic field due to a current passing through a coil.
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  C)
   Producing induced current in a coil due to relative motion between a magnet and the coil.
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  D)
   The process of rotating a coil of an electric motor.
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• question_answer4)
  At the time of short circuit, the current in the circuit
  A)
   Reduces substantially
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  B)
   does not change.
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  C)
   Increases heavily
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  D)
   vary continuously
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• question_answer5)
  For dynamo which one of the following statements is correct
  A)
   It converts the electrical energy into light energy
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  B)
   It converts the kinetic energy into heat energy
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  C)
   It converts the mechanical energy into electrical energy
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  D)
   It converts the electrical energy into mechanical energy
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• question_answer6)
  A conducting wire is dropped along east-west direction, then
  A)
   No emf is induced
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  B)
   No induced current flows
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  C)
   Induced current flows from west to east
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  D)
   Induced current flows from east to west
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• question_answer7)
  Core of transformer is made up of
  A)
   Soft iron          
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  B)
   Steel
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  C)
   Iron                 
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  D)
   Alnico
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• question_answer8)
  Fan is based on
  A)
   Electric Motor
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  B)
   Electric dynamo
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  C)
   Both               
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  D)
   None of these
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• question_answer9)
  The core of a transformer is laminated so that
  A)
   Ratio of voltage in the primary and secondary may be increased
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  B)
   Rusting of the core may be stopped
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  C)
   Energy losses due to eddy currents may be reduced
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  D)
   Change in flux is increased
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• question_answer10)
  Large transformers, when used for some time, become hot and are cooled by circulating oil. The heating of transformer is due to
  A)
   Heating effect of current alone
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  B)
   Hysteresis loss alone
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  C)
   Both the hysteresis loss and heating effect of current
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  D)
   None of the above
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• question_answer11)
  Alternating current cannot be measured by dc ammeter because
  A)
   ac cannot pass through dc ammeter
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  B)
   Average value of complete cycle is zero
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  C)
   ac is virtual
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  D)
   ac changes its direction
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• question_answer12)
  A bulb is connected first with DC and then AC of same voltage it will shine brightly with
  A)
   AC
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  B)
   DC
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  C)
   Brightness will be in ratio 1/1.4
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  D)
   Equally with both
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• question_answer13)
  The voltage of domestic AC is 220 volt. What does this represent
  A)
   Mean voltage   
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  B)
   Peak voltage
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  C)
   Root mean voltage        
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  D)
   Root mean square voltage
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• question_answer14)
  Radio frequency choke uses core of
  A)
   Air      
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  B)
          Iron
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  C)
   Air and Iron     
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  D)
               None of these
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• question_answer15)
  Quantity that remains unchanged in a transformer is
  A)
   Voltage
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  B)
   Current
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  C)
   Frequency        
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  D)
   None of the above
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• question_answer16)
  For high frequency, a capacitor offers
  A)
   More reactance
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  B)
   Less reactance
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  C)
   Zero reactance
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  D)
          Infinite reactance
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• question_answer17)
  When the number of turns in a coil is doubled without any change in the length of the coil, its self-inductance becomes
  A)
   Four times
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  B)
   Doubled
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  C)
   Halved
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  D)
   Unchanged
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• question_answer18)
  When a metallic plate swings between the poles of a magnet
  A)
   No effect on the plate
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  B)
   Eddy current are set up inside the plate and the direction of the current is along the motion of the plate
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  C)
   Eddy currents are set up inside the plate and the direction of the current oppose the motion of the plate
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  D)
   Eddy currents are set up inside the plate
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• question_answer19)
  A long horizontal metallic rod with length along the east-west direction is falling under gravity. The potential difference between its two ends will be
  A)
   Zero                
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  B)
   Constant
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  C)
   Increase with time
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  D)
   Decrease with time
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• question_answer20)
  What is the function of oil in a transformer?
  A)
   It provides insulation     
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  B)
   It provides cooling
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  C)
   It provides smoothness
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  D)
   Both [a] and [b]
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