Electrical Machines
The sparking at the the brushes, in a DC machines is due to

 presence of commutator.
 high resistance of carbon brushes.
  reactance voltage.
 armature reaction.

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Electrical Machines
In case of a DC Shunt motor if the load is decreased to some extent, what will happen to its speed?

 The speed will increase abruptly.
 The speed will increase gradually.
 The speed will increase in proportion to reduction in load.
 The speed will remains almost constant.

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