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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. In a parallel circuit...
Amperes.
746 watts.
Higher current with voltage remaining the same.
A. Total resistance is less than the smallest resistor.

2. What voltage is required to force 5 amps through a 15-ohm resistor?
Hydrogen.
Stays the same.
75 volts.
Clean water.

3. What is the first step in treating a chemical burn of the eye?
Wattmeter.
Flush the burn the clean water.
75 volts.
Series-wound.

4. The most common reason that solid state devices fail is...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Repel each other.
Flush thoroughly with water.
Heat

5. Not true about electrical shocks?
75 volts.
Burns will appear only at the point where contact is made to the energized circuit.
Ammeter.
Soft iron.

6. What is the opposition to flow of electric current?
Current
Hydrogen.
Resistance.
A. Total resistance is less than the smallest resistor.

7. Like poles of a magnet will...
Repel each other.
Voltage.
Attract each other.
Heat

8. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
37.3 kilowatts
Ohmmeter.
Less than the resistance of either resistor.

9. What is Ohm's Law?
Decrease.
Stays the same.
Direct current.
E=IR.

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

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11. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
4.0 ohms.
Ammeter.
Ohms.
No.4 AWG.

12. What should be used in treating an eye injury caused by battery acid?
Ventilation.
Clean water.
Direct current.
Stays the same.

13. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Repel each other.
In series.
75 volts.
Power.

14. The advantage of DC over AC is that DC offers...
48 volts
Wattmeter.
Power.
Better speed control on motors.

15. How many kilowatts are used to develop 50 horsepower?
Heat
Hydrogen.
746 watts.
37.3 kilowatts

16. What is the flow of electrons in a conductor?
In series.
It must prevent internal explosions.
A counter-EMF.
Current.

17. Define direct current...
The movement of electrons in a circuit.
Clean water.
Current that flows in only one direction.
No.4 AWG.

18. The longer the conductor - the greater the...
Resistance.
Treat for physical shock.
Ohmmeter.
Hydrogen.

19. Storage battery charging stations must be provided with what kind of current protection?
Distance.
Reverse.
48 ohms.
Soft iron.

20. The explosive gas that is generated when a battery is charging is...
A bi-directional device that can pass current in either direction.
After charging
Ohmmeter.
Hydrogen.

21. The instrument used to check the electrolyte of a battery is a...
75 volts.
6 volts.
Hydrometer.
Watts.

22. Current in a series circuit...
Watts.
Stays the same.
E=IR.
Reverse.

23. What must be provided at underground battery charging stations?
Ventilation.
In parallel.
746 watts.
Decrease.

24. Resistance is measured with a...
6 volts.
Ohmmeter.
Resistance.
60 ohms.

25. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
Higher current with voltage remaining the same.
Repel each other.
Clean water.

26. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
36 volts.
Attract each other.
No.4 AWG.

27. The combined resistance of two resistors in parallel is...
100 ohms
Distance.
Less than the resistance of either resistor.
A bi-directional device that can pass current in either direction.

28. How must two 12-volt batteries be connected in order to increase the current capacity?
Stays the same.
Heat
Wattmeter.
In parallel.

29. Unlike poles of a magnet will...
Less than the resistance of either resistor.
Watts.
Flush the burn the clean water.
Attract each other.

30. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Clean water.
Voltmeter.
In series.
Ventilation.

31. Voltage in a parallel circuit...
96 volts.
Stays the same.
400 ampere-hours.
Repel each other.

32. 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...
Current that flows in one direction only.
Treat for physical shock.
Amperes.
Attract each other.

33. The unit of measurement of power is...
Watts.
The opposition to flow of electrons in a circuit.
A bi-directional device that can pass current in either direction.
Flush thoroughly with water.

34. Not a requirement of an explosion-proof enclosure?
It must prevent internal explosions.
After charging
E=IR.
Stays the same.

35. Define resistance...
Repel each other.
Wattmeter.
The opposition to flow of electrons in a circuit.
8 ohms.

36. A triac is?
A bi-directional device that can pass current in either direction.
6 volts.
It must prevent internal explosions.
Repel each other.

37. The best insulator against the lines of magnetic force is...
Distance.
Decrease.
A wire wound resistor.
Reverse.

38. The unit of measurement of resistance is?
Better speed control on motors.
8 ohms.
Ohms.
400 ampere-hours.

39. What is the total voltage of two 6-volt batteries connected in parallel?
6 volts.
E=IR.
Voltmeter.
A. Total resistance is less than the smallest resistor.

40. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Less than the resistance of either resistor.
Burns will appear only at the point where contact is made to the energized circuit.
400 ampere-hours.
Stays the same.

41. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Ammeter.
100 ohms
60 ohms.
8 ohms.

42. Resistors are rated in ohms and...
The opposition to flow of electrons in a circuit.
Current
Watts.
E=IR.

43. What voltage would be required to force 10 amps through a 20-ohm resistor?
8 ohms.
200 volts
4.8 ohms
Repel each other.

44. Not an electro-magnet?
A wire wound resistor.
It must prevent internal explosions.
Watts.
A. Total resistance is less than the smallest resistor.

45. The specific gravity of the electrolyte of a fully charged battery should be...
Ammeter.
1.260 to 1.280.
Ventilation.
A bi-directional device that can pass current in either direction.

46. Which current flows in only one direction?
Direct current.
500 volts.
15 minutes.
48 ohms.

47. Define current...
100 ohms
E=IR.
The movement of electrons in a circuit.
746 watts.

48. Trailing cable on DC-powered mobile haulage equipment must be at least...
Burns will appear only at the point where contact is made to the energized circuit.
60 ohms.
No.4 AWG.
Flush thoroughly with water.

49. Which of the following is a requirement of an explosion-proof enclosure?
Decrease.
500 volts.
Heat
It must prevent ignition of surrounding methane atmosphere.

50. What is the total resistance of three 16-ohm resistors connected in series?
15 minutes.
Current that flows in only one direction.
48 ohms.
Current