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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...
37.3 kilowatts
A. Total resistance is less than the smallest resistor.
Better speed control on motors.
Until the victim receives medical attention.

2. Current is measured with a (an)...
4.0 ohms.
Ammeter.
E=IR.
In parallel.

3. Not a requirement of an explosion-proof enclosure?
500 volts.
Distance.
It must prevent internal explosions.
48 ohms.

4. What must be provided at underground battery charging stations?
Attract each other.
Distance.
Ventilation.
No.4 AWG.

5. What is the total resistance of three 16-ohm resistors connected in series?
Treat for physical shock.
Series-wound.
No.4 AWG.
48 ohms.

6. Unlike poles of a magnet will...
Hydrometer.
Attract each other.
Series-wound.
Resistance.

7. The unit of measurement of resistance is?
Ohms.
Distance.
Clean water.
96 volts.

8. What voltage would be required to force 10 amps through a 50-ohm resistor?
200 volts
500 volts.
Ohmmeter.
Power.

9. Resistors are rated in ohms and...
37.3 kilowatts
Current that flows in one direction only.
Hydrogen.
Watts.

10. What is the total voltage of four 9-volt batteries connected in a series?
36 volts.
15 minutes.
48 ohms.
Current

11. Current in a series circuit...
Burns will appear only at the point where contact is made to the energized circuit.
Ohms.
In parallel.
Stays the same.

12. Power is measured with a...
8 ohms.
Watts.
Wattmeter.
The movement of electrons in a circuit.

13. The explosive gas that is generated when a battery is charging is...
Hydrogen.
Distance.
Reverse.
A wire wound resistor.

14. What is the total voltage of eight 12-volt batteries connected in series?
Current
Stays the same.
96 volts.
Attract each other.

15. The core of an electro-magnet should be made of...
Current.
Soft iron.
In series.
36 volts.

16. Which of the following motors CANNOT be run without a load?
Amperes.
No.4 AWG.
Voltmeter.
Series-wound.

17. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Hydrogen.
Stays the same.
Attract each other.
Watts.

18. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
E=IR.
Hydrogen.
Series-wound.
4.0 ohms.

19. Voltage is measured with a...
No.4 AWG.
746 watts.
Voltmeter.
Decrease.

20. The best insulator against the lines of magnetic force is...
Soft iron.
Distance.
In parallel.
Reverse.

21. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
A wire wound resistor.
Treat for physical shock.
8 ohms.

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

23. The unit of measurement of current is...
8 ohms.
A bi-directional device that can pass current in either direction.
Amperes.
4.8 ohms

24. What is the rate that work is done or heat is dissipated?
Better speed control on motors.
Soft iron.
Clean water.
Power.

25. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Stays the same.
60 ohms.
No.4 AWG.
Hydrometer.

26. If the cross-sectional area of a conductor is increased - its resistance will...
36 volts.
Stays the same.
Decrease.
Burns will appear only at the point where contact is made to the energized circuit.

27. Which current flows in only one direction?
Direct current.
Ohms.
400 ampere-hours.
Until the victim receives medical attention.

28. The advantage of DC over AC is that DC offers...
746 watts.
In series.
Better speed control on motors.
A bi-directional device that can pass current in either direction.

29. Which of the following is a requirement of an explosion-proof enclosure?
Wattmeter.
It must prevent ignition of surrounding methane atmosphere.
Better speed control on motors.
60 ohms.

30. When should water be added to a battery?
After charging
Attract each other.
In parallel.
A counter-EMF.

31. What is the opposition to flow of electric current?
No.4 AWG.
Decrease.
4.0 ohms.
Resistance.

32. Which of the following stays the same in all parts of a series circuit?
Current
Flush thoroughly with water.
No.4 AWG.
In series.

33. Batteries connected in parallel provide...
Higher current with voltage remaining the same.
96 volts.
1.260 to 1.280.
Watts.

34. How many kilowatts are used to develop 50 horsepower?
48 volts
400 ampere-hours.
37.3 kilowatts
Decrease.

35. Define direct current...
60 ohms.
Current that flows in one direction only.
No.4 AWG.
In series.

36. 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...
In series.
Watts.
Treat for physical shock.
In series.

37. Chemical burns caused by battery acid should be washed with clean water for at least...
36 volts.
15 minutes.
Hydrogen.
Compound-wound and shunt-wound.

38. Which of the following motors are considered to be constant or nearly constant speed?
4.0 ohms.
400 ampere-hours.
Reverse.
Compound-wound and shunt-wound.

39. Resistance is measured with a...
Ventilation.
Ohmmeter.
A. Total resistance is less than the smallest resistor.
Repel each other.

40. How long should treatment for shock be continued?
Until the victim receives medical attention.
Watts.
37.3 kilowatts
Flush the burn the clean water.

41. What is the total resistance of four 15-ohm resistors connected in series?
Current that flows in one direction only.
60 ohms.
8 ohms.
Attract each other.

42. Like poles of a magnet will...
Repel each other.
Decrease.
E=IR.
Current that flows in one direction only.

43. What is the total voltage of four 12-volt batteries connected in series?
48 volts
6 volts.
Power.
Hydrometer.

44. What voltage is required to force 5 amps through a 15-ohm resistor?
Wattmeter.
Power.
75 volts.
Watts.

45. The longer the conductor - the greater the...
Treat for physical shock.
48 volts
Resistance.
200 volts

46. What is the total resistance of four 25-ohm resistors connected in series?
Wattmeter.
100 ohms
Current that flows in only one direction.
A. Total resistance is less than the smallest resistor.

47. How many watts are in one horsepower?
Flush thoroughly with water.
In series.
746 watts.
A. Total resistance is less than the smallest resistor.

48. The most common reason that solid state devices fail is...
Heat
Ohmmeter.
Attract each other.
36 volts.

49. What is Ohm's Law?
Ohms.
E=IR.
Less than the resistance of either resistor.
In series.

50. What is the first step in treating a chemical burn of the eye?
E=IR.
Flush the burn the clean water.
Current that flows in only one direction.
8 ohms.