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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 four 12-volt batteries connected in series?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
48 volts
Ventilation.
500 volts.

2. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
746 watts.
Current that flows in only one direction.
No.4 AWG.

3. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Current.
E=IR.
In series.
Reverse.

4. How many watts are in one horsepower?
In series.
746 watts.
Treat for physical shock.
Less than the resistance of either resistor.

5. Which of the following stays the same in all parts of a series circuit?
Resistance.
It must prevent internal explosions.
Current that flows in one direction only.
Current

6. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
Direct current.
Wattmeter.
Hydrogen.

7. What is the total voltage of eight 12-volt batteries connected in series?
96 volts.
Flush thoroughly with water.
Ammeter.
Ohmmeter.

8. What is Ohm's Law?
The opposition to flow of electrons in a circuit.
Wattmeter.
E=IR.
Better speed control on motors.

9. How long should treatment for shock be continued?
8 ohms.
Clean water.
Until the victim receives medical attention.
The opposition to flow of electrons in a circuit.

10. The explosive gas that is generated when a battery is charging is...
The movement of electrons in a circuit.
Direct current.
Current
Hydrogen.

11. Define direct current...
Reverse.
A counter-EMF.
Current that flows in one direction only.
75 volts.

12. Batteries connected in parallel provide...
Distance.
Until the victim receives medical attention.
Hydrogen.
Higher current with voltage remaining the same.

13. How many kilowatts are used to develop 50 horsepower?
Flush the burn the clean water.
37.3 kilowatts
Wattmeter.
After charging

14. Define direct current...
Power.
In series.
Current that flows in only one direction.
A bi-directional device that can pass current in either direction.

15. What voltage would be required to force 10 amps through a 20-ohm resistor?
36 volts.
A counter-EMF.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
200 volts

16. Define current...
Watts.
Stays the same.
The movement of electrons in a circuit.
Current

17. Voltage in a parallel circuit...
Clean water.
Stays the same.
200 volts
Flush thoroughly with water.

18. Not a requirement of an explosion-proof enclosure?
15 minutes.
Current.
No.4 AWG.
It must prevent internal explosions.

19. Unlike poles of a magnet will...
Repel each other.
746 watts.
100 ohms
Attract each other.

20. When should water be added to a battery?
After charging
Stays the same.
A wire wound resistor.
60 ohms.

21. The longer the conductor - the greater the...
Resistance.
Watts.
Flush the burn the clean water.
A bi-directional device that can pass current in either direction.

22. Current in a series circuit...
Until the victim receives medical attention.
Heat
Watts.
Stays the same.

23. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
Power.
36 volts.
Burns will appear only at the point where contact is made to the energized circuit.

24. Power is measured with a...
8 ohms.
After charging
Watts.
Wattmeter.

25. What must be provided at underground battery charging stations?
Ventilation.
Attract each other.
37.3 kilowatts
Heat

26. Which current flows in only one direction?
200 volts
6 volts.
Clean water.
Direct current.

27. What is the flow of electrons in a conductor?
Decrease.
Current.
Hydrometer.
Ventilation.

28. What is the first step in treating a chemical burn of the eye?
Flush the burn the clean water.
60 ohms.
Resistance.
Resistance.

29. The unit of measurement of resistance is?
Distance.
The movement of electrons in a circuit.
A wire wound resistor.
Ohms.

30. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Hydrometer.
Higher current with voltage remaining the same.
8 ohms.
Less than the resistance of either resistor.

31. What is the rate that work is done or heat is dissipated?
Flush the burn the clean water.
Hydrogen.
Power.
Flush thoroughly with water.

32. Like poles of a magnet will...
Current that flows in only one direction.
Current that flows in one direction only.
Repel each other.
Watts.

33. What voltage would be required to force 10 amps through a 50-ohm resistor?
Repel each other.
Current that flows in only one direction.
Soft iron.
500 volts.

34. Resistance is measured with a...
Ohmmeter.
No.4 AWG.
In series.
Ammeter.

35. The unit of measurement of current is...
37.3 kilowatts
Amperes.
8 ohms.
Compound-wound and shunt-wound.

36. What is the total resistance of four 15-ohm resistors connected in series?
60 ohms.
Repel each other.
Voltmeter.
Attract each other.

37. The advantage of DC over AC is that DC offers...
96 volts.
Attract each other.
No.4 AWG.
Better speed control on motors.

38. Trailing cable on DC-powered mobile haulage equipment must be at least...
1.260 to 1.280.
400 ampere-hours.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
No.4 AWG.

39. What is the total resistance of four 25-ohm resistors connected in series?
Current that flows in one direction only.
37.3 kilowatts
100 ohms
Burns will appear only at the point where contact is made to the energized circuit.

40. Not an electro-magnet?
Until the victim receives medical attention.
Decrease.
A wire wound resistor.
Current

41. The most common reason that solid state devices fail is...
Wattmeter.
In series.
Heat
Repel each other.

42. Voltage is measured with a...
Voltmeter.
After charging
In series.
The opposition to flow of electrons in a circuit.

43. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
A counter-EMF.
It must prevent ignition of surrounding methane atmosphere.
No.4 AWG.

44. What is the unit of electromotive force or electric pressure?
96 volts.
Series-wound.
Until the victim receives medical attention.
Voltage.

45. If the cross-sectional area of a conductor is increased - its resistance will...
Amperes.
In parallel.
4.0 ohms.
Decrease.

46. 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...
Reverse.
It must prevent internal explosions.
Treat for physical shock.
746 watts.

47. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
It must prevent internal explosions.
A. Total resistance is less than the smallest resistor.
In series.
200 volts

48. What should be used in treating an eye injury caused by battery acid?
Wattmeter.
After charging
Clean water.
A. Total resistance is less than the smallest resistor.

49. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
100 ohms
4.0 ohms.
400 ampere-hours.
In series.

50. Storage battery charging stations must be provided with what kind of current protection?
The opposition to flow of electrons in a circuit.
Hydrogen.
Reverse.
Ohms.