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DC Theory

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. If the victim of an electrical shock has been burned while in contact with electricity - the first treatment you should apply - if the victim's heart and respiratory system are still functioning - is to...
Burns will appear only at the point where contact is made to the energized circuit.
Series-wound.
Treat for physical shock.
400 ampere-hours.

2. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Stays the same.
Hydrogen.
200 volts
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

3. When should water be added to a battery?
After charging
48 volts
In parallel.
Heat

4. What must be provided at underground battery charging stations?
6 volts.
E=IR.
Ventilation.
8 ohms.

5. What is the total voltage of eight 12-volt batteries connected in series?
6 volts.
96 volts.
48 volts
37.3 kilowatts

6. The explosive gas that is generated when a battery is charging is...
200 volts
Hydrogen.
Voltmeter.
In series.

7. How must two 12-volt batteries be connected in order to increase the current capacity?
Voltmeter.
In parallel.
Watts.
Voltage.

8. What should be used in treating an eye injury caused by battery acid?
Hydrometer.
Clean water.
Distance.
Stays the same.

9. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
A. Total resistance is less than the smallest resistor.
8 ohms.
No.4 AWG.
Power.

10. The unit of measurement of resistance is?
Ohms.
A counter-EMF.
Current that flows in only one direction.
In series.

11. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Hydrometer.
In parallel.
A. Total resistance is less than the smallest resistor.
No.4 AWG.

12. The advantage of DC over AC is that DC offers...
Repel each other.
Current that flows in one direction only.
37.3 kilowatts
Better speed control on motors.

13. What is the total resistance of three 16-ohm resistors connected in series?
Soft iron.
48 ohms.
No.4 AWG.
Flush the burn the clean water.

14. Define direct current...
Current that flows in only one direction.
Decrease.
Direct current.
15 minutes.

15. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Compound-wound and shunt-wound.
Reverse.
4.8 ohms
Current that flows in only one direction.

16. Resistors are rated in ohms and...
Watts.
Better speed control on motors.
No.4 AWG.
37.3 kilowatts

17. A triac is?
The opposition to flow of electrons in a circuit.
In series.
Repel each other.
A bi-directional device that can pass current in either direction.

18. What voltage is required to force 5 amps through a 15-ohm resistor?
Ohmmeter.
100 ohms
48 volts
75 volts.

19. What is the total voltage of two 6-volt batteries connected in parallel?
6 volts.
A bi-directional device that can pass current in either direction.
Less than the resistance of either resistor.
Hydrometer.

20. What is the total voltage of four 9-volt batteries connected in a series?
After charging
36 volts.
The opposition to flow of electrons in a circuit.
Ohmmeter.

21. Voltage in a parallel circuit...
Stays the same.
Power.
Watts.
Treat for physical shock.

22. The instrument used to check the electrolyte of a battery is a...
48 volts
Hydrometer.
Decrease.
A counter-EMF.

23. Which of the following motors are considered to be constant or nearly constant speed?
Voltage.
Current that flows in one direction only.
Compound-wound and shunt-wound.
Hydrogen.

24. The first step in treating a chemical burn - such as one caused by battery acid - is to...
After charging
Flush thoroughly with water.
Series-wound.
60 ohms.

25. What is the total voltage of four 12-volt batteries connected in series?
500 volts.
Wattmeter.
Less than the resistance of either resistor.
48 volts

26. Define current...
Watts.
Watts.
Reverse.
The movement of electrons in a circuit.

27. Unlike poles of a magnet will...
Hydrometer.
Attract each other.
No.4 AWG.
It must prevent internal explosions.

28. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
1.260 to 1.280.
8 ohms.
In series.
Voltmeter.

29. Not a requirement of an explosion-proof enclosure?
Soft iron.
4.0 ohms.
It must prevent internal explosions.
A bi-directional device that can pass current in either direction.

30. Current in a series circuit...
Current
Stays the same.
Heat
37.3 kilowatts

31. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
The opposition to flow of electrons in a circuit.
48 volts
Voltage.

32. The core of an electro-magnet should be made of...
6 volts.
A. Total resistance is less than the smallest resistor.
Soft iron.
Wattmeter.

33. Not an electro-magnet?
A wire wound resistor.
A. Total resistance is less than the smallest resistor.
Ventilation.
Current

34. Power is measured with a...
Current that flows in one direction only.
Watts.
Heat
Wattmeter.

35. Not true about electrical shocks?
Attract each other.
48 ohms.
Burns will appear only at the point where contact is made to the energized circuit.
Flush the burn the clean water.

36. The best insulator against the lines of magnetic force is...
Less than the resistance of either resistor.
A counter-EMF.
In series.
Distance.

37. Like poles of a magnet will...
Flush thoroughly with water.
746 watts.
Burns will appear only at the point where contact is made to the energized circuit.
Repel each other.

38. Chemical burns caused by battery acid should be washed with clean water for at least...
Ventilation.
15 minutes.
A. Total resistance is less than the smallest resistor.
Hydrogen.

39. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
Direct current.
Watts.
Watts.

40. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Stays the same.
400 ampere-hours.
746 watts.
Direct current.

41. Batteries connected in parallel provide...
Higher current with voltage remaining the same.
Burns will appear only at the point where contact is made to the energized circuit.
Voltage.
Voltmeter.

42. What is the opposition to flow of electric current?
Series-wound.
Watts.
After charging
Resistance.

43. Define resistance...
Current that flows in one direction only.
Current that flows in only one direction.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
The opposition to flow of electrons in a circuit.

44. The specific gravity of the electrolyte of a fully charged battery should be...
Stays the same.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
37.3 kilowatts
1.260 to 1.280.

45. What voltage would be required to force 10 amps through a 50-ohm resistor?
48 volts
15 minutes.
500 volts.
The opposition to flow of electrons in a circuit.

46. Which of the following stays the same in all parts of a series circuit?
Repel each other.
Current
No.4 AWG.
A. Total resistance is less than the smallest resistor.

47. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
Higher current with voltage remaining the same.
Stays the same.
200 volts

48. What is Ohm's Law?
The opposition to flow of electrons in a circuit.
E=IR.
Current that flows in only one direction.
200 volts

49. How many watts are in one horsepower?
A bi-directional device that can pass current in either direction.
In parallel.
746 watts.
Burns will appear only at the point where contact is made to the energized circuit.

50. What voltage would be required to force 10 amps through a 20-ohm resistor?
Burns will appear only at the point where contact is made to the energized circuit.
Current that flows in one direction only.
Voltage.
200 volts