DC Generator MCQ

81. A simple method of increasing the voltage of a DC generator is

1. to decrease the air gap flux density
   
2. to increase the speed of rotation
   
3. to decrease the speed of rotation
   
4. to increase the length of the armature

82. The e.m.f. of a DC generator depends on

1. commutation
   
2. speed
   
3. frequency
   
4. brush contact drop

83. Which one of the following generators are used for charging batteries?

1. compound generator
   
2. shunt generator
   
3. series generator
   
4. tacho generator

84. DC shunt generator has

1. slightly drooping characteristic curve
   
2. appreciably rising characteristics
   
3. constant voltage characteristics
   
4. appreciably falling characteristics

85. An external resistance added in the field of a d.c. shunt generator will

1. increase the speed of the generator
   
2. increase the voltage of the generator
   
3. decrease the voltage of the generator
   
4. increase the power delivered

86. Shunt generators are most suited for stable parallel operation as their voltage characteristics are

1. drooping
   
2. identical
   
3. linear
   
4. rising

87. Brushes are provided in DC machine for

1. smooth rotation
   
2. preventing sparking
   
3. providing a path for the flow of current
   
4. reducing the losses

88. The EMF induced in the armature of a shunt generator is 500 V. The armature resistance is 0.2 ohm if the armature current is 200 A, what is the terminal voltage?

1. 500 V
   
2. 520 V
   
3. 460 V
   
4. 540 V

89. What happens if the magnetic neutral axis coincides with the geometrical neutral axis in case of DC generator

1. the generator runs on designed speed
   
2. the generator runs on overload
3. there is no load on the generator
4. the generator runs at full load

90. Where the shunt generators are widely used?

1. Where the load is very high
   
2. Where a constant voltage is required over a narrow load range
   
3. Where often fluctuation occurred
   
4. None of the above