Title MCQ ELECTRIC MOTORS AND TRANSFORMERS.pdf ✅

Way to Polytechnic ❖ Way to Polytechnic ELECTRIC MOTORS AND TRANSFORMERS Unit -I DC Generators 1. What is the primary function of the commutator in a DC generator? a. Voltage regulation b. Current rectification c. Commutation of brushes d. Armature winding 2. Which rule is used to determine the direction of induced current in a DC generator? a. Fleming's Left Hand Rule b. Fleming's Right Hand Rule c. Lenz's Law d. Ohm's Law 3. In a DC generator, what is the purpose of the armature winding? a. To produce a magnetic field b. To connect the brushes c. To generate electrical power d. To control voltage 4. The E.M.F. equation of a DC generator is given by: a. E = IR b. E = V - IR c. E = ΦZNP/60A d. E = I/R 5. What is the effect of armature reaction in a DC generator? a. Increases voltage b. Reduces voltage c. No effect on voltage d. Reverses voltage 6. Which of the following is a part of a DC generator? a. Stator b. Commutator c. Slip rings d. Rotor 7. The classification of measuring instruments into indicating, recording, and integrating instruments is based on their: a. Sensitivity
Way to Polytechnic b. Accuracy c. Display method d. Purpose of use 8. What is the schematic diagram used to represent a DC generator? a. V-I curve b. P-V diagram c. Circle diagram d. Gantt chart 9. Which law governs the commutation process in a DC generator? a. Ampere's Law b. Ohm's Law c. Faraday's Law d. Lenz's Law 10. In a DC generator, what material is commonly used for the construction of the armature core? a. Copper b. Aluminum c. Iron d. Silver 11. What is the function of brushes in a DC generator? a. To support the rotor b. To create a magnetic field c. To provide electrical contact with the commutator d. To control voltage 12. Which type of DC generator is commonly used in applications requiring constant voltage? a. Series generator b. Shunt generator c. Compound generator d. Separately excited generator 13. The process of reversing the current in the coil sides as they pass through the magnetic field is known as: a. Rectification b. Saturation c. Commutation d. Excitation 14. What is the purpose of the field winding in a DC generator? a. To produce a magnetic field 2
Way to Polytechnic b. To control armature reaction c. To support the brushes d. To regulate voltage 15. The formula E = ΦZNP/60A is used to calculate: a. Commutation b. Armature reaction c. E.M.F. of a DC generator d. Brush voltage drop 16. Which of the following applications is NOT a common use of DC generators? a. Battery charging b. Electric vehicles c. Power grid distribution d. Portable generators 17. What is the purpose of the air gap in a DC generator? a. To improve efficiency b. To reduce friction c. To provide insulation d. To allow for cooling 18. Indicating instruments are primarily used for: a. Recording data over time b. Instantaneous measurement of a quantity c. Integrating measurements d. Storing electrical energy 19. The principle of operation of a DC generator is based on: a. Electromagnetic induction b. Photoelectric effect c. Thermoelectric effect d. Piezoelectric effect 20. In a DC generator, what term is used to describe the unwanted voltage drop across the brushes and commutator? a. Armature reaction b. Commutation loss c. Brush voltage drop d. Core loss 3
Way to Polytechnic Answers: 1. c. Commutation of brushes 2. b. Fleming's Right Hand Rule 3. c. To generate electrical power 4. c. E = ΦZNP/60A 5. b. Reduces voltage 6. b. Commutator 7. c. Display method 8. c. Circle diagram 9. c. Faraday's Law 10. c. Iron 11. c. To provide electrical contact with the commutator 12. b. Shunt generator 13. c. Commutation 14. a. To produce a magnetic field 15. c. E.M.F. of a DC generator 16. c. Power grid distribution 17. a. To improve efficiency 18. b. Instantaneous measurement of a quantity 19. a. Electromagnetic induction 20. c. Brush voltage drop 4