Railways Basic Science and Engineering Electricity and Circuits Question Bank

done Basic Electricity Total Questions - 50

• question_answer1)
  In a current carrying conductor the net charge is
  A)
   \[1.6\times {{10}^{-19}}\]coulomb done clear
  B)
   \[6.25\times {{10}^{-18}}\]coulomb done clear
  C)
   zero done clear
  D)
   infinite done clear
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• question_answer2)
  When no current is passed through a conductor,
  A)
   the free electrons do not move done clear
  B)
   the average speed of a free electron over a large period of time is not zero done clear
  C)
   the average velocity of a free electron over a large period of time is zero done clear
  D)
   the average of the velocities of all the free electrons at an instant is non zero done clear
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• question_answer3)
  A current passes through a wire of non-uniform cross section. Which of the following quantities are independent of the cross-section?
  A)
   The charge crossing done clear
  B)
   Drift velocity               done clear
  C)
   Current density done clear
  D)
   Free-electron density done clear
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• question_answer4)
  In the equation AB = C, A is the current density, C is the electric field, Then B is
  A)
   resistivity                      done clear
  B)
   conductivity done clear
  C)
   potential difference         done clear
  D)
   resistance done clear
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• question_answer5)
  The speed at which the current travels, in conductor, is nearly equal to
  A)
   \[3\times {{10}^{4}}m/s\]                    done clear
  B)
  \[3\times {{10}^{5}}m/s\] done clear
  C)
  \[4\times {{10}^{6}}m/s\]                     done clear
  D)
   \[3\times {{10}^{8}}m/s\] done clear
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• question_answer6)
  When a potential difference V is applied across a conductor at a temperature T, the drift velocity of electrons is proportional to
  A)
   \[\sqrt{V}\]                               done clear
  B)
   V done clear
  C)
   \[\sqrt{T}\]                                done clear
  D)
   T done clear
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• question_answer7)
  For which of the following dependence of drift velocity \[{{v}_{d}}\]on electric field E, is Ohm's law obeyed?
  A)
   \[{{v}_{d}}\propto {{E}^{2}}\]                       done clear
  B)
   \[{{v}_{d}}={{E}^{1/2}}\] done clear
  C)
   \[{{v}_{d}}\]= constant            done clear
  D)
   \[{{v}_{d}}=E\] done clear
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• question_answer8)
  The current density (number of free electrons per\[{{m}^{3}}\]) in metallic conductor is of the order of
  A)
   1022                done clear
  B)
   1024 done clear
  C)
   1026                            done clear
  D)
   1028 done clear
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• question_answer9)
  A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it
  A)
   increases, thermal velocity of the electron increases done clear
  B)
   decreases, thermal velocity of the electron increases done clear
  C)
   increases, thermal velocity of the electron decreases done clear
  D)
   decreases, thermal velocity of the electron decreases done clear
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• question_answer10)
  The electric field intensity E, current density J and specific resistance k are related to each other through the relation
  A)
   E=J/k              done clear
  B)
   E=J k done clear
  C)
   E=k/J              done clear
  D)
   k=J E done clear
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• question_answer11)
  The unit of specific resistance is
  A)
   \[\Omega \,\,{{m}^{-1}}\]                    done clear
  B)
   \[{{\Omega }^{-1}}\,\,{{m}^{-1}}\] done clear
  C)
   \[{{\Omega }^{-1}}\]   done clear
  D)
   \[2.5\Omega {{m}^{2}}\] done clear
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• question_answer12)
  The example of non-ohmic resistance is
  A)
   diode                done clear
  B)
   copper wire done clear
  C)
   filament lamp                done clear
  D)
   carbon resistor done clear
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• question_answer13)
  Constantan wire is used for making standard resistance, because it has
  A)
   high melting point done clear
  B)
   low specific resistance done clear
  C)
   high specific resistance done clear
  D)
   negligible temperature coefficient of resistance done clear
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• question_answer14)
  At temperature \[0{}^\circ K\], the germanium behaves as a/an
  A)
   conductor                     done clear
  B)
   insulator done clear
  C)
   super?conductor done clear
  D)
   ferromagnetic done clear
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• question_answer15)
  Which of the following is used for the formation of thermistor?
  A)
   Copper oxide     done clear
  B)
   Nickel oxide done clear
  C)
   Iron oxide                     done clear
  D)
   All of the above done clear
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• question_answer16)
  What is the suitable material for electric fuse?
  A)
   Cu                               done clear
  B)
   Constantan done clear
  C)
   Tin-lead alloy                done clear
  D)
   Nichrome done clear
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• question_answer17)
  The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then
  A)
   the resistance and the specific resistance, will both remain unchanged done clear
  B)
   the resistance will be doubled and the specific resistance will be halved done clear
  C)
   the resistance will be halved and the specific resistance will remain unchanged done clear
  D)
   the resistance will be halved and the specific resistance will be doubled done clear
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• question_answer18)
  Appliances based on heating effect of current work on
  A)
   only a. c. done clear
  B)
   only d. c. done clear
  C)
   both a. c. and d. c. done clear
  D)
  d) None of these done clear
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• question_answer19)
  In the series combination of two or more than two resistances
  A)
   the current through each resistance is same done clear
  B)
   the voltage through each resistance is same done clear
  C)
   neither current nor voltage through each resistance is same done clear
  D)
   both current and voltage through each resistance are same. done clear
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• question_answer20)
  The energy of a charged capacitor resides in
  A)
    the electric field only done clear
  B)
   the magnetic field only done clear
  C)
   Both the electric and magnetic fields done clear
  D)
   Neither in electric nor magnetic field done clear
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• question_answer21)
  The capacity of a spherical conductor is 1 pf then its diameter would be
  A)
   1.8 m               done clear
  B)
   \[1.8\times {{10}^{4}}m\] done clear
  C)
   \[1.8\times {{10}^{3}}m\]                    done clear
  D)
   \[1.8\times {{10}^{10}}m\] done clear
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• question_answer22)
  Check the correct relation
  A)
   Potential = Charge/Capacity done clear
  B)
   Charge = Potential/Capacity done clear
  C)
   Capacity = Potential \[\times \] Charge done clear
  D)
   Potential = Capacity \[\times \] Charge done clear
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• question_answer23)
  Which of the following has negative temperature coefficient of resistance?
  A)
   Tungsten                       done clear
  B)
   Carbon done clear
  C)
   Mercury                        done clear
  D)
   Dynamite done clear
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• question_answer24)
  The temperature coefficient of resistance of conductors is
  A)
   positive             done clear
  B)
   negative done clear
  C)
   neutral              done clear
  D)
   None of these done clear
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• question_answer25)
  In a circuit containing two unequal resistors connected in parallel, then
  A)
   the current is same in both the resistors done clear
  B)
   the current is larger in larger resistance done clear
  C)
   the voltage drop is same across both the resistances done clear
  D)
   the voltage drop is larger across larger resistances done clear
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• question_answer26)
  Which of the following is an ohmic conductor?
  A)
   Copper             done clear
  B)
   Silver done clear
  C)
   Gold                            done clear
  D)
   All of these done clear
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• question_answer27)
  Reciprocal of specific resistance is
  A)
   conductive resistance done clear
  B)
   specific conductance done clear
  C)
    specific reactance done clear
  D)
   plate resistance done clear
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• question_answer28)
  The safe current for the fuse wire of radius r is I, then
  A)
   \[I\,\alpha \,{{r}^{1/2}}\]                     done clear
  B)
   \[I\,\alpha \,r\] done clear
  C)
   \[I\,\alpha \,{{r}^{3/2}}\]                     done clear
  D)
   \[I\,\alpha \,{{r}^{2}}\] done clear
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• question_answer29)
  The resistance of a straight conductor does not depend upon its
  A)
   shape of cross-section     done clear
  B)
   temperature done clear
  C)
    material                       done clear
  D)
   length done clear
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• question_answer30)
  The specific resistance of all metals is most affected by
  A)
   temperature                   done clear
  B)
   pressure done clear
  C)
   degree of illumination     done clear
  D)
   charge carriers done clear
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• question_answer31)
  The element in an electric stove is made of
  A)
   copper              done clear
  B)
   nichrome done clear
  C)
   platinum                       done clear
  D)
   tungsten done clear
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• question_answer32)
  The example of non-ohmic resistance is
  A)
   copper wire                   done clear
  B)
   nichrome wire done clear
  C)
   diode                done clear
  D)
   tungsten wire done clear
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• question_answer33)
  The conductivity of a superconductor is
  A)
   infinite  done clear
  B)
   very large done clear
  C)
   very small                     done clear
  D)
   zero done clear
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• question_answer34)
  When the temperature of metallic conductor is increased, its resistance
  A)
   always decreases done clear
  B)
   always increases done clear
  C)
   may increase or decrease done clear
  D)
   remains the same done clear
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• question_answer35)
  Electric current is a quantity of
  A)
   scalar   done clear
  B)
   vector done clear
  C)
   Both [a] and [b] done clear
  D)
   None of these done clear
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• question_answer36)
  The specific resistance of a wire depends upon
  A)
    its length                      done clear
  B)
   its cross-sectional area done clear
  C)
    its dimensions          done clear
  D)
   its material done clear
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• question_answer37)
  The temperature coefficient of resistance of some material is negative. The material is
  A)
   silicon               done clear
  B)
   aluminum done clear
  C)
   arsenide                        done clear
  D)
   germanium done clear
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• question_answer38)
  What is converted into heat when current is set-up through a conductor?
  A)
    Electric current  done clear
  B)
   Electric potential done clear
  C)
   Electric energy   done clear
  D)
   None of these done clear
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• question_answer39)
  For which of the following substances the temperature coefficient of resistivity is positive?
  A)
   Carbon             done clear
  B)
   Germanium done clear
  C)
   Cadmium                     done clear
  D)
   Aluminium done clear
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• question_answer40)
  The total capacitance of two capacitors\[{{C}_{1}}\]and \[{{C}_{2}}\]connected in series will be
  A)
   less than smallest capacitor done clear
  B)
   more than the highest capacitance done clear
  C)
   equal to the highest capacitance done clear
  D)
   equal to \[{{C}_{1}}+{{C}_{2}}\] done clear
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• question_answer41)
  Which of the following is an active component?
  A)
   Inductor                        done clear
  B)
   Capacitor done clear
  C)
   Resistor             done clear
  D)
   Diode done clear
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• question_answer42)
  What is The Basic Three Electrical Quantities?
  A)
   Resistance, Capacitance, Inductance done clear
  B)
   Power, Voltage, Conductance done clear
  C)
   Voltage, Current, Resistance (Impedance) done clear
  D)
   Current, Reluctance, Inductance done clear
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• question_answer43)
  In case of Short Circuit, ____Current will flow in the Circuit.
  A)
   Zero                             done clear
  B)
   Very Low done clear
  C)
   Normal             done clear
  D)
   Infinite done clear
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• question_answer44)
  Siemens or Mho \[(\mho )\] is the unit of___?
  A)
   Conductance                 done clear
  B)
   Admittance done clear
  C)
   Both 1 & 2                   done clear
  D)
   None of the above done clear
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• question_answer45)
  Electric pressure is also called
  A)
   Resistance                     done clear
  B)
   Power done clear
  C)
   Voltage             done clear
  D)
   Energy done clear
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• question_answer46)
  The dielectric material used in variable capacitor is generally
  A)
    Mica               done clear
  B)
   Air done clear
  C)
    Ceramic                       done clear
  D)
   Electrolyte done clear
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• question_answer47)
  Power consumed in a pure inductive circuit is
  A)
   Zero                             done clear
  B)
   Less done clear
  C)
   High                             done clear
  D)
   Infinity done clear
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• question_answer48)
  Frequency of direct current is
  A)
   Zero                             done clear
  B)
   Unity done clear
  C)
  (e) 50 Hz                       done clear
  D)
   infinity done clear
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• question_answer49)
  Power factor of direct current is
  A)
   Zero                             done clear
  B)
   Lagging done clear
  C)
   Unity    done clear
  D)
   Leading done clear
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• question_answer50)
  The property of a conductor due to which it passes current is called
  A)
   Reluctance                    done clear
  B)
   Conductance done clear
  C)
   Admittance                   done clear
  D)
   Inductance done clear
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