This set of Automobile Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Charging System”.
1. Which component in the DC generator produces a magnetic field?
a) Stator
b) Commutator
c) Armature
d) Carbon brushes
View Answer
Explanation: Carbon brushes produce the magnetic field in DC generator. The DC generator is a device which converts mechanical energy into electrical energy. It works on the principle of induced EMF.
2. Which component in alternator produces a magnetic field?
a) Frame
b) Stator
c) Regulator
d) Rotor
View Answer
Explanation: Rotor in an alternator produces a magnetic field. An alternator is a device that converts mechanical energy to electrical energy and produces the AC current. The rotor is the moving part of the alternator.
3. Why is a thermistor used in an alternator regulator?
a) To control maximum current
b) To control maximum voltage
c) To compensate for temperature change
d) To control minimum current
View Answer
Explanation: A thermistor is used in an alternator regulator to compensate for temperature change. It is a temperature-sensing device. It alters its physical resistance to change temperature.
4. What is the frequency of a vibrating contact type regulator for DC generator?
a) 20 per second
b) 200 per second
c) 200 per minute
d) 20 per minute
View Answer
Explanation: The frequency of a vibrating contact type regulator for DC generator is 200 per second. The main parts of the DC generator are frame, armature, and field coils. The parts of the armature are shaft, core, commutator and coil windings.
5. At the start of the engine, the charging voltage is _______
a) Lower
b) Higher
c) Same
d) Zero
View Answer
Explanation: The charging voltage is high at the start of the engine. The charging voltage should be less than the alternator voltage to charge the battery. The standard battery automotive battery should indicate 12.6 V at 35℃. When the engine is running, it should show 13.7 V to 14.7 V.
6. In an alternator, which component controls the output?
a) Voltage regulator
b) Cutout relay
c) Current regulator
d) Diode
View Answer
Explanation: Voltage regulator controls the output of the alternator. A voltage regulator is designed so that it keeps a constant voltage level. The voltage regulator is used when the steady and reliable voltage is needed.
7. What is the material of an alternator frame?
a) Cast iron
b) Brass
c) Copper
d) Aluminum
View Answer
Explanation: An alternator frame is made of aluminum. Aluminum is lightweight. It is no-magnetic. It has a higher thermal conductivity so as to keep the alternator assembly cool by more efficient transfer of heat.
8. If the lead-acid cell has a total of 17 cells, then what is the number of positive plates?
a) 9
b) 8
c) 7
d) 6
View Answer
Explanation: The number of positive plates in the lead-acid cell is always one less than the number of negative plates. The number of negative plates = 9 and total plates are = 17, therefore, a number of positive plates = 8.
9. Which of the following is not an advantage of the alternator?
a) Higher output
b) Lower weight
c) Less maintenance
d) High efficiency
View Answer
Explanation: With a lightweight of the alternator, the efficiency of alternator increases. As the output current does not flow through the commutator and brushes, thus surface contamination is eliminated.
10. Field coils in a generator produce permanent magnet.
a) True
b) False
View Answer
Explanation: Field coils in a generator produce a temporary magnet. The field magnets are electromagnets. These magnets are energized by generator current. The fields magnets have a small residual magnetism this helps in providing the initial field to start the generator operation.
Sanfoundry Global Education & Learning Series – Automobile Engineering.
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