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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. What is the total voltage of eight 12-volt batteries connected in series?
Hydrometer.
In series.
36 volts.
96 volts.

2. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
Amperes.
500 volts.
Hydrogen.

3. Define current...
Current that flows in only one direction.
After charging
Current
The movement of electrons in a circuit.

4. What voltage would be required to force 10 amps through a 20-ohm resistor?
Attract each other.
6 volts.
200 volts
A bi-directional device that can pass current in either direction.

5. What is the unit of electromotive force or electric pressure?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Voltage.
Ohmmeter.
Wattmeter.

6. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
48 ohms.
It must prevent internal explosions.
In series.

7. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
6 volts.
Treat for physical shock.
Amperes.

8. The advantage of DC over AC is that DC offers...
4.8 ohms
Current
Better speed control on motors.
Stays the same.

9. What is the opposition to flow of electric current?
Resistance.
Current that flows in only one direction.
In series.
1.260 to 1.280.

10. If the cross-sectional area of a conductor is increased - its resistance will...
1.260 to 1.280.
48 volts
Decrease.
500 volts.

11. The unit of measurement of power is...
Watts.
No.4 AWG.
Until the victim receives medical attention.
48 ohms.

12. What is the total resistance of four 15-ohm resistors connected in series?
In series.
Current.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
60 ohms.

13. What must be provided at underground battery charging stations?
Ventilation.
Flush the burn the clean water.
Resistance.
Less than the resistance of either resistor.

14. The core of an electro-magnet should be made of...
Decrease.
Soft iron.
500 volts.
Until the victim receives medical attention.

15. Which of the following motors CANNOT be run without a load?
Series-wound.
Until the victim receives medical attention.
Decrease.
746 watts.

16. Power is measured with a...
Wattmeter.
Ohms.
In parallel.
A. Total resistance is less than the smallest resistor.

17. What is Ohm's Law?
No.4 AWG.
E=IR.
It must prevent internal explosions.
No.4 AWG.

18. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
75 volts.
400 ampere-hours.
Hydrometer.
The opposition to flow of electrons in a circuit.

19. The most common reason that solid state devices fail is...
Heat
48 volts
No.4 AWG.
Current.

20. The armature of a direct current motor - when running - generates...
Burns will appear only at the point where contact is made to the energized circuit.
A counter-EMF.
400 ampere-hours.
Ammeter.

21. Define direct current...
500 volts.
Watts.
Current that flows in only one direction.
Ohms.

22. Which of the following stays the same in all parts of a series circuit?
Amperes.
Attract each other.
Current
Reverse.

23. The explosive gas that is generated when a battery is charging is...
Higher current with voltage remaining the same.
Current that flows in one direction only.
Hydrogen.
Reverse.

24. The longer the conductor - the greater the...
The movement of electrons in a circuit.
Resistance.
Ammeter.
Current.

25. Define resistance...
The opposition to flow of electrons in a circuit.
60 ohms.
75 volts.
A bi-directional device that can pass current in either direction.

26. Voltage in a parallel circuit...
15 minutes.
Stays the same.
Resistance.
36 volts.

27. Trailing cable on DC-powered mobile haulage equipment must be at least...
Clean water.
No.4 AWG.
36 volts.
Attract each other.

28. What should be used in treating an eye injury caused by battery acid?
60 ohms.
Clean water.
Wattmeter.
It must prevent internal explosions.

29. The unit of measurement of current is...
Higher current with voltage remaining the same.
Amperes.
Heat
Current.

30. Current is measured with a (an)...
60 ohms.
1.260 to 1.280.
Stays the same.
Ammeter.

31. How must two 12-volt batteries be connected in order to increase the current capacity?
In parallel.
Amperes.
Current that flows in only one direction.
Current.

32. Not a requirement of an explosion-proof enclosure?
4.8 ohms
It must prevent internal explosions.
It must prevent ignition of surrounding methane atmosphere.
Voltage.

33. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Reverse.
15 minutes.
In series.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

34. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Series-wound.
No.4 AWG.
It must prevent ignition of surrounding methane atmosphere.
60 ohms.

35. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
Heat
The movement of electrons in a circuit.
200 volts

36. What is the total voltage of four 9-volt batteries connected in a series?
36 volts.
Voltage.
48 volts
Heat

37. When should water be added to a battery?
After charging
60 ohms.
36 volts.
Amperes.

38. Current in a series circuit...
Stays the same.
Voltmeter.
Ammeter.
Clean water.

39. The instrument used to check the electrolyte of a battery is a...
Hydrogen.
Hydrometer.
Current that flows in one direction only.
Ohmmeter.

40. What is the flow of electrons in a conductor?
No.4 AWG.
Current.
96 volts.
The opposition to flow of electrons in a circuit.

41. Define direct current...
Hydrogen.
Clean water.
Voltage.
Current that flows in one direction only.

42. A triac is?
E=IR.
Current that flows in only one direction.
A bi-directional device that can pass current in either direction.
1.260 to 1.280.

43. What is the hazard of pouring water into battery acid 'electrolyte'?

44. Not true about electrical shocks?
Current
The opposition to flow of electrons in a circuit.
Burns will appear only at the point where contact is made to the energized circuit.
75 volts.

45. 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...
37.3 kilowatts
Power.
Stays the same.
Treat for physical shock.

46. How many kilowatts are used to develop 50 horsepower?
It must prevent internal explosions.
Distance.
In parallel.
37.3 kilowatts

47. Like poles of a magnet will...
In parallel.
746 watts.
Repel each other.
Better speed control on motors.

48. The specific gravity of the electrolyte of a fully charged battery should be...
Resistance.
1.260 to 1.280.
Burns will appear only at the point where contact is made to the energized circuit.
Watts.

49. Chemical burns caused by battery acid should be washed with clean water for at least...
Ammeter.
A wire wound resistor.
15 minutes.
Hydrogen.

50. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
4.0 ohms.
60 ohms.
Voltage.
Watts.