2 September 2016

ELECTRICAL QUESTIONS AND ANSWERS-MCQ 10-ETO


QUESTIONS AND ANSWERS FOR ETO

1. Since fuse elements are made of zinc or any alloy of tin and lead, the melting point of the fuse element must be _____________.               
A. higher than that of copper         
B. lower than that of copper          
C. equal to that of copper               
D. reached when the conductor it is protecting becomes "white hot."              
Ans : B

2. Which of the following statements correctly applies to  transistors?              
A. NDN and PNP are the two basic types of transistors.         
B. The three terminals are called the emitter, base, and  collector.   
C. The emitter separates the base and collector.     
D. The collector separates the emitter and base.    
Ans : B

3. The basic measuring unit of inductance is the _________.               
A. coulomb          
B. ohm  
C. farad
D. henry               
Ans : D

4. Which of the listed precautions should be taken when  cleaning the internals of a motor with compressed air?               
A. Open the machine on both ends so as to allow the air and dust to escape.  
B. Be certain that the circuit breaker is opened and tagged on the feeder panel.          
C. Be certain that the air is clean and as dry as possible.        
D. All of the above.           
Ans : D

5. The purpose of DC generator brushes is to _____________.            
A. neutralize armature reaction   
B. conduct electric current to an outside circuit       
C. convert DC current to AC current             
D. provide excitation to a DC generator     
Ans : B

6. The most common source of excitation for synchronous motors is a/an ______________.     
A. Step up transformer    
B. half-wave rectifier        
C. DC supply        
D. AC supply        
Ans : C

7. Fuses are rated in _____________.         
A. voltage            
B. amperage       
C. interrupting capacity   
D. all the above  
Ans : D

8. Which of the following statements comparing transistors and vacuum tubes is correct?         
A. Both transistors and vacuum tubes have a cathode that must be heated to give off electrons.             
B. A vacuum tube must have a heated cathode, where transistors do not.      
C. Neither transistors nor vacuum tubes require heat for  electrons to flow.    
D. The anode of both transistors and vacuum tubes must be  heated to give off electrons.         
Ans : B

9. Which of the following statements concerning nickel-cadmium batteries is true?
A. When mixing electrolyte always add acid to the water.    
B. Nickel-cadmium batteries can be charged and discharged only a limited number of times without damage to the cells.               
C. Nickel-cadmium batteries can be stored for a long time and still keep a full charge without additional charging.            
D. The electrolyte of an idle nickel-cadmium battery must be replaced monthly to maintain battery condition.   
Ans : C

10. Power transformers are rated in _____________.           
A. kilowatts         
B. ampere-turns
C. kilowatt-volts 
D. kilovolt-amperes           
Ans : D

11. Which of the listed precautions should be observed before spraying liquid solvent on the insulation of an electric motor?          
A. Slow the motor down to low speed.        
B. Disconnect the motor from the power source.    
C. Secure all ventilation in the area.             
D. Preheat the insulation to assist in cleaning.          
Ans : B

12. The simplest method of controlling the terminal voltage of compound-wound DC generator is with a _____________.             
A. hand-operated field rheostat connected in series with the shunt field circuit              
B. separate exciter in a series with the shunt field   
C. carbon pile regulator in series with the load         
D. balance coil diverting neutral current through the shunt field         
Ans : A

13. The type of control circuit that will not permit automatic restarting after power is restored, following a power failure is called _____________.               
A. low voltage protection
B. low voltage release      
C. overload lockout           
D. reduced voltage restart             
Ans : A

14. Local action in a nickel-cadmium battery is offset by  _____________.      
A. separating the positive and negative plates with plastic spacers    
B. separating the positive and negative plates with resin impregnated spacers              
C. adding a small amount of lithium hydroxide to the   electrolyte      
D. trickle charging             
Ans : D

15. Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in _____________.               
A. ohms
B. mhos
C. henrys              
D. farads              
Ans : C

16. An insulation resistance test is performed on a particular piece of electric equipment. In addition to the resistance reading, what information listed below should be entered in the electrical log?        
A. The maximum allowable operating temperature of the machine.
B. The temperature of the machine at the time the resistance reading was taken.       
C. The normal temperature rise of the machine.      
D. The complete nameplate data from the resistance test  instrument used to obtain the reading.         
Ans : B

17. A compound generator has a no-load voltage of 250 volts anda full-load voltage of 230 volts, and therefore, is  considered to be _____________.
A. flat compounded          
B. over compounded        
C. under compounded      
D. terminal compounded
Ans : C

18. Which of the following types of motors is often designed for use in correcting power factor?
A. Polyphase       
B. Wound-rotor  
C. Induction         
D. Synchronous  
Ans : D

19. Electric cables are formed of stranded wire to ____________.    
A. increase the current carrying capability for a given size wire           
B. increase their flexibility               
C. decrease the weight for a given size wire              
D. assure good conductivity at junction points          
Ans : B

20. A device which prints out a permanent record of the plant operating conditions is known as the _____________.       
A. analogger       
B. bell logger      
C. alarm logger  
D. data logger    
Ans : D

21. Alternating current circuits develop resistance, inductance, and capacitance. The capacitance of individual capacitors is expressed in _____________.           
A. ohms
B. mhos
C. henrys              
D. farads              
Ans : D

22. One method of testing for a reversed shunt field coil in a DC generator or motor is by connecting the field to a direct current source, at reduced field rated voltage, and test for polarity using a/an ____________.               
A. iron bar across each field            
B. magnetic compass placed near each field             
C. test lamp across adjacent fields
D. copper jumper across the inter pole connections
Ans : B

23. Which of the following statements represents the important factor that must be considered when replacing a faulty diode in the exciter rectifier assembly?
A. Be certain that the replacement diode is the same polarity as the one removed.     
B. Never alter the diode alignment to cause a change in the neutral plane.    
C. Replacement of a diode also requires balancing of the rotor with a one-piece rotor lamination to be shrunk fit and keyed to the shaft.    
D. The replacement diode must be dipped in varnish prior to installation to protect against humidity.
Ans : A

24. Which solid AWG wire size has the smallest physical   cross-sectional area?              
A. 12     
B. 14     
C. 16      
D. 18     
Ans : D

25. A lead-acid battery is considered fully charged when the ______________.             
A. electrolyte gasses freely             
B. battery charger ammeter indicates a positive reading      
C. terminal voltage reaches a constant value at a given  temperature              
D. specific gravity of all cells reaches the correct value and no longer increases over a period of 1 to 4 hours

Ans : D

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ELECTRICAL QUESTIONS AND ANSWERS-MCQ 10-ETO
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