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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. How long should treatment for shock be continued?
4.0 ohms.
Watts.
37.3 kilowatts
Until the victim receives medical attention.

2. The core of an electro-magnet should be made of...
60 ohms.
Higher current with voltage remaining the same.
Hydrogen.
Soft iron.

3. The unit of measurement of power is...
6 volts.
Watts.
Current
Repel each other.

4. What is the total voltage of four 12-volt batteries connected in series?
4.0 ohms.
48 volts
Ventilation.
Amperes.

5. Define resistance...
Higher current with voltage remaining the same.
Direct current.
The opposition to flow of electrons in a circuit.
6 volts.

6. What is the unit of electromotive force or electric pressure?
Wattmeter.
Voltage.
In series.
Flush the burn the clean water.

7. The specific gravity of the electrolyte of a fully charged battery should be...
1.260 to 1.280.
Flush the burn the clean water.
A wire wound resistor.
Watts.

8. Define direct current...
Heat
A. Total resistance is less than the smallest resistor.
Current that flows in only one direction.
Burns will appear only at the point where contact is made to the energized circuit.

9. Storage battery charging stations must be provided with what kind of current protection?
Better speed control on motors.
Ohmmeter.
Reverse.
The opposition to flow of electrons in a circuit.

10. The armature of a direct current motor - when running - generates...
In series.
A counter-EMF.
Ohmmeter.
Better speed control on motors.

11. Current is measured with a (an)...
Reverse.
48 ohms.
Ammeter.
Current

12. Define current...
Hydrometer.
The movement of electrons in a circuit.
100 ohms
A counter-EMF.

13. Which of the following motors CANNOT be run without a load?
4.8 ohms
Series-wound.
200 volts
Current that flows in only one direction.

14. The combined resistance of two resistors in parallel is...
Current that flows in only one direction.
Less than the resistance of either resistor.
Wattmeter.
Amperes.

15. What is the total resistance of three 16-ohm resistors connected in series?
It must prevent ignition of surrounding methane atmosphere.
Direct current.
48 ohms.
Distance.

16. Voltage in a parallel circuit...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
48 volts
A counter-EMF.
Stays the same.

17. The instrument used to check the electrolyte of a battery is a...
Until the victim receives medical attention.
The movement of electrons in a circuit.
Hydrometer.
Current.

18. 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...
Treat for physical shock.
No.4 AWG.
Voltage.
Current

19. What voltage would be required to force 10 amps through a 20-ohm resistor?
200 volts
A. Total resistance is less than the smallest resistor.
Repel each other.
Reverse.

20. The unit of measurement of resistance is?
Reverse.
Ohms.
Ammeter.
Ohmmeter.

21. Batteries connected in parallel provide...
A. Total resistance is less than the smallest resistor.
In series.
Higher current with voltage remaining the same.
Reverse.

22. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
Higher current with voltage remaining the same.
100 ohms
Less than the resistance of either resistor.

23. The best insulator against the lines of magnetic force is...
No.4 AWG.
36 volts.
Amperes.
Distance.

24. What is Ohm's Law?
Watts.
Clean water.
E=IR.
48 volts

25. What is the total voltage of two 6-volt batteries connected in parallel?
36 volts.
Attract each other.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
6 volts.

26. What should be used in treating an eye injury caused by battery acid?
Clean water.
Heat
4.0 ohms.
Repel each other.

27. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Wattmeter.
In series.
400 ampere-hours.
Direct current.

28. Not true about electrical shocks?
In parallel.
Burns will appear only at the point where contact is made to the energized circuit.
No.4 AWG.
37.3 kilowatts

29. The longer the conductor - the greater the...
Resistance.
Power.
4.0 ohms.
A counter-EMF.

30. The explosive gas that is generated when a battery is charging is...
37.3 kilowatts
Hydrogen.
Until the victim receives medical attention.
Ohms.

31. A triac is?
48 ohms.
A bi-directional device that can pass current in either direction.
Series-wound.
96 volts.

32. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
Attract each other.
Hydrometer.
Current that flows in one direction only.

33. If the cross-sectional area of a conductor is increased - its resistance will...
Decrease.
Until the victim receives medical attention.
48 ohms.
It must prevent ignition of surrounding methane atmosphere.

34. What voltage is required to force 5 amps through a 15-ohm resistor?
Hydrometer.
Hydrogen.
75 volts.
Flush the burn the clean water.

35. Which of the following is a requirement of an explosion-proof enclosure?
1.260 to 1.280.
It must prevent ignition of surrounding methane atmosphere.
Ohms.
Amperes.

36. Which of the following stays the same in all parts of a series circuit?
Current
75 volts.
Less than the resistance of either resistor.
No.4 AWG.

37. Resistors are rated in ohms and...
Ohms.
Watts.
Ohmmeter.
37.3 kilowatts

38. Which current flows in only one direction?
Direct current.
60 ohms.
The opposition to flow of electrons in a circuit.
Resistance.

39. Which of the following motors are considered to be constant or nearly constant speed?
Hydrogen.
E=IR.
Compound-wound and shunt-wound.
1.260 to 1.280.

40. Not an electro-magnet?
Attract each other.
A wire wound resistor.
A counter-EMF.
Ammeter.

41. In a parallel circuit...
Series-wound.
Hydrogen.
Amperes.
A. Total resistance is less than the smallest resistor.

42. Chemical burns caused by battery acid should be washed with clean water for at least...
500 volts.
Compound-wound and shunt-wound.
Until the victim receives medical attention.
15 minutes.

43. What is the total resistance of four 25-ohm resistors connected in series?
A wire wound resistor.
1.260 to 1.280.
Reverse.
100 ohms

44. The unit of measurement of current is...
A. Total resistance is less than the smallest resistor.
Amperes.
In parallel.
200 volts

45. What must be provided at underground battery charging stations?
Repel each other.
4.0 ohms.
Ventilation.
Decrease.

46. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Burns will appear only at the point where contact is made to the energized circuit.
Current
400 ampere-hours.
8 ohms.

47. 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'.
Compound-wound and shunt-wound.
96 volts.
No.4 AWG.

48. How must two 12-volt batteries be connected in order to increase the current capacity?
Ohms.
In parallel.
Ammeter.
After charging

49. What is the total resistance of four 15-ohm resistors connected in series?
60 ohms.
Voltmeter.
500 volts.
Watts.

50. Trailing cable on DC-powered mobile haulage equipment must be at least...
Decrease.
Amperes.
No.4 AWG.
Repel each other.