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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 voltage is required to force 5 amps through a 15-ohm resistor?
Clean water.
Higher current with voltage remaining the same.
75 volts.
A wire wound resistor.

2. The most common reason that solid state devices fail is...
Flush the burn the clean water.
Compound-wound and shunt-wound.
Heat
A counter-EMF.

3. The instrument used to check the electrolyte of a battery is a...
Hydrometer.
1.260 to 1.280.
Direct current.
Series-wound.

4. What is the total voltage of four 9-volt batteries connected in a series?
Amperes.
Direct current.
In series.
36 volts.

5. The core of an electro-magnet should be made of...
500 volts.
The opposition to flow of electrons in a circuit.
No.4 AWG.
Soft iron.

6. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Wattmeter.
In series.
The opposition to flow of electrons in a circuit.
Voltmeter.

7. What is the total voltage of four 12-volt batteries connected in series?
Resistance.
Better speed control on motors.
48 volts
A wire wound resistor.

8. Resistance is measured with a...
Watts.
4.8 ohms
Ohmmeter.
In series.

9. What is the opposition to flow of electric current?
4.0 ohms.
Resistance.
Voltage.
A counter-EMF.

10. Define direct current...
A wire wound resistor.
Current that flows in only one direction.
4.0 ohms.
60 ohms.

11. In a parallel circuit...
Higher current with voltage remaining the same.
Series-wound.
In series.
A. Total resistance is less than the smallest resistor.

12. Which of the following motors CANNOT be run without a load?
E=IR.
96 volts.
Series-wound.
Wattmeter.

13. Which of the following motors are considered to be constant or nearly constant speed?
E=IR.
48 ohms.
Resistance.
Compound-wound and shunt-wound.

14. Like poles of a magnet will...
Repel each other.
96 volts.
8 ohms.
A counter-EMF.

15. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Attract each other.
No.4 AWG.
Hydrogen.
400 ampere-hours.

16. How many watts are in one horsepower?
Treat for physical shock.
746 watts.
Reverse.
Attract each other.

17. What should be used in treating an eye injury caused by battery acid?
Clean water.
In parallel.
8 ohms.
The movement of electrons in a circuit.

18. Current is measured with a (an)...
Ammeter.
Less than the resistance of either resistor.
Decrease.
No.4 AWG.

19. What is the total resistance of three 16-ohm resistors connected in series?
Flush thoroughly with water.
In parallel.
Resistance.
48 ohms.

20. Unlike poles of a magnet will...
Resistance.
Attract each other.
37.3 kilowatts
A bi-directional device that can pass current in either direction.

21. The combined resistance of two resistors in parallel is...
Treat for physical shock.
Distance.
In series.
Less than the resistance of either resistor.

22. How long should treatment for shock be continued?
Until the victim receives medical attention.
746 watts.
37.3 kilowatts
In series.

23. Voltage is measured with a...
96 volts.
Voltmeter.
Attract each other.
Compound-wound and shunt-wound.

24. What voltage would be required to force 10 amps through a 50-ohm resistor?
100 ohms
500 volts.
Hydrometer.
60 ohms.

25. Define direct current...
60 ohms.
48 volts
Current that flows in one direction only.
The opposition to flow of electrons in a circuit.

26. The unit of measurement of current is...
Amperes.
Heat
Reverse.
746 watts.

27. Resistors are rated in ohms and...
Watts.
37.3 kilowatts
Amperes.
96 volts.

28. 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...
Soft iron.
The movement of electrons in a circuit.
Distance.
Treat for physical shock.

29. When should water be added to a battery?
Watts.
After charging
6 volts.
200 volts

30. What is the total voltage of two 6-volt batteries connected in parallel?
Better speed control on motors.
Current.
6 volts.
Flush thoroughly with water.

31. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
Less than the resistance of either resistor.
Watts.
Soft iron.

32. If the cross-sectional area of a conductor is increased - its resistance will...
Ohms.
Decrease.
A bi-directional device that can pass current in either direction.
Voltmeter.

33. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Decrease.
Heat
746 watts.
400 ampere-hours.

34. What is Ohm's Law?
After charging
E=IR.
8 ohms.
The movement of electrons in a circuit.

35. Not a requirement of an explosion-proof enclosure?
A counter-EMF.
37.3 kilowatts
Reverse.
It must prevent internal explosions.

36. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
Resistance.
4.8 ohms
Watts.

37. The specific gravity of the electrolyte of a fully charged battery should be...
96 volts.
Ohmmeter.
Until the victim receives medical attention.
1.260 to 1.280.

38. How must two 12-volt batteries be connected in order to increase the current capacity?
Stays the same.
96 volts.
In parallel.
Decrease.

39. Current in a series circuit...
Stays the same.
In series.
6 volts.
Direct current.

40. Trailing cable on DC-powered mobile haulage equipment must be at least...
Amperes.
No.4 AWG.
In series.
Hydrogen.

41. Which current flows in only one direction?
Direct current.
Repel each other.
Clean water.
Decrease.

42. Which of the following stays the same in all parts of a series circuit?
A counter-EMF.
75 volts.
Current
15 minutes.

43. The longer the conductor - the greater the...
Current that flows in only one direction.
36 volts.
8 ohms.
Resistance.

44. The explosive gas that is generated when a battery is charging is...
Burns will appear only at the point where contact is made to the energized circuit.
Hydrogen.
Less than the resistance of either resistor.
75 volts.

45. The advantage of DC over AC is that DC offers...
Compound-wound and shunt-wound.
Series-wound.
Stays the same.
Better speed control on motors.

46. What is the total resistance of four 15-ohm resistors connected in series?
Current that flows in only one direction.
37.3 kilowatts
60 ohms.
Clean water.

47. Define resistance...
In series.
The opposition to flow of electrons in a circuit.
Voltage.
746 watts.

48. What is the first step in treating a chemical burn of the eye?
A wire wound resistor.
The movement of electrons in a circuit.
Flush the burn the clean water.
Flush thoroughly with water.

49. The unit of measurement of power is...
Compound-wound and shunt-wound.
Until the victim receives medical attention.
Watts.
It must prevent internal explosions.

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

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