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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. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
In series.
Amperes.
Current
Ammeter.

2. The longer the conductor - the greater the...
Voltage.
48 volts
Resistance.
Ohmmeter.

3. What voltage is required to force 5 amps through a 15-ohm resistor?
Wattmeter.
75 volts.
Compound-wound and shunt-wound.
37.3 kilowatts

4. Current is measured with a (an)...
Voltage.
Ammeter.
Stays the same.
Stays the same.

5. A triac is?
Hydrometer.
Hydrogen.
36 volts.
A bi-directional device that can pass current in either direction.

6. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
It must prevent internal explosions.
400 ampere-hours.
Current.

7. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Stays the same.
Stays the same.
In series.
Hydrogen.

8. What is the rate that work is done or heat is dissipated?
Power.
No.4 AWG.
6 volts.
Hydrometer.

9. 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...
48 volts
Treat for physical shock.
Watts.
Repel each other.

10. How many watts are in one horsepower?
Current that flows in only one direction.
Hydrogen.
4.0 ohms.
746 watts.

11. What should be used in treating an eye injury caused by battery acid?
Clean water.
Ventilation.
Resistance.
Attract each other.

12. The explosive gas that is generated when a battery is charging is...
Ventilation.
Hydrogen.
100 ohms
Stays the same.

13. The armature of a direct current motor - when running - generates...
Watts.
A counter-EMF.
Ohms.
36 volts.

14. How long should treatment for shock be continued?
48 ohms.
It must prevent internal explosions.
Until the victim receives medical attention.
4.8 ohms

15. What must be provided at underground battery charging stations?
E=IR.
Ventilation.
100 ohms
Reverse.

16. The core of an electro-magnet should be made of...
Hydrometer.
Stays the same.
Soft iron.
Voltage.

17. Not a requirement of an explosion-proof enclosure?
It must prevent internal explosions.
No.4 AWG.
A. Total resistance is less than the smallest resistor.
Distance.

18. Not true about electrical shocks?
No.4 AWG.
Distance.
Burns will appear only at the point where contact is made to the energized circuit.
48 ohms.

19. Batteries connected in parallel provide...
Distance.
Watts.
Higher current with voltage remaining the same.
The opposition to flow of electrons in a circuit.

20. What is the unit of electromotive force or electric pressure?
Voltage.
Power.
Hydrogen.
No.4 AWG.

21. Like poles of a magnet will...
E=IR.
100 ohms
Treat for physical shock.
Repel each other.

22. Resistance is measured with a...
Ohmmeter.
Direct current.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Voltage.

23. What is the total voltage of four 9-volt batteries connected in a series?
36 volts.
48 volts
In series.
Burns will appear only at the point where contact is made to the energized circuit.

24. Which of the following motors are considered to be constant or nearly constant speed?
Current that flows in one direction only.
Compound-wound and shunt-wound.
Until the victim receives medical attention.
Repel each other.

25. Trailing cable on DC-powered mobile haulage equipment must be at least...
No.4 AWG.
746 watts.
In series.
36 volts.

26. What is the opposition to flow of electric current?
Resistance.
A wire wound resistor.
1.260 to 1.280.
Voltage.

27. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Hydrogen.
Watts.
60 ohms.
48 ohms.

28. What is the total resistance of four 25-ohm resistors connected in series?
No.4 AWG.
Voltmeter.
100 ohms
60 ohms.

29. If the cross-sectional area of a conductor is increased - its resistance will...
Amperes.
Direct current.
Flush thoroughly with water.
Decrease.

30. When should water be added to a battery?
After charging
Treat for physical shock.
E=IR.
A. Total resistance is less than the smallest resistor.

31. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
In series.
4.0 ohms.
Stays the same.
In parallel.

32. The unit of measurement of resistance is?
Until the victim receives medical attention.
200 volts
60 ohms.
Ohms.

33. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
Higher current with voltage remaining the same.
Power.
No.4 AWG.

34. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
Watts.
No.4 AWG.
It must prevent internal explosions.

35. Current in a series circuit...
4.0 ohms.
A bi-directional device that can pass current in either direction.
Higher current with voltage remaining the same.
Stays the same.

36. Define current...
The movement of electrons in a circuit.
48 volts
Resistance.
Direct current.

37. Which of the following motors CANNOT be run without a load?
Soft iron.
Series-wound.
Watts.
A bi-directional device that can pass current in either direction.

38. The instrument used to check the electrolyte of a battery is a...
Current that flows in only one direction.
Hydrometer.
Attract each other.
A counter-EMF.

39. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Direct current.
Hydrogen.
No.4 AWG.
The opposition to flow of electrons in a circuit.

40. Which current flows in only one direction?
Direct current.
Clean water.
Repel each other.
Current

41. What is the total voltage of two 6-volt batteries connected in parallel?
Treat for physical shock.
Amperes.
Watts.
6 volts.

42. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Amperes.
4.8 ohms
48 ohms.
Ammeter.

43. What is the total voltage of eight 12-volt batteries connected in series?
Hydrogen.
96 volts.
The movement of electrons in a circuit.
Stays the same.

44. Power is measured with a...
Wattmeter.
Burns will appear only at the point where contact is made to the energized circuit.
4.8 ohms
Amperes.

45. Not an electro-magnet?
Current that flows in one direction only.
Amperes.
Compound-wound and shunt-wound.
A wire wound resistor.

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

47. The most common reason that solid state devices fail is...
Heat
The movement of electrons in a circuit.
Flush thoroughly with water.
No.4 AWG.

48. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
8 ohms.
Ammeter.
6 volts.

49. What voltage would be required to force 10 amps through a 20-ohm resistor?
Hydrogen.
Compound-wound and shunt-wound.
Resistance.
200 volts

50. Voltage is measured with a...
Voltmeter.
4.0 ohms.
Series-wound.
Until the victim receives medical attention.