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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. Current in a series circuit...
Ohmmeter.
Stays the same.
746 watts.
Heat

2. The unit of measurement of power is...
Watts.
No.4 AWG.
The movement of electrons in a circuit.
Hydrometer.

3. Not an electro-magnet?
200 volts
4.8 ohms
Ammeter.
A wire wound resistor.

4. What is the total resistance of four 15-ohm resistors connected in series?
Voltmeter.
60 ohms.
Resistance.
Amperes.

5. What is the total resistance of three 16-ohm resistors connected in series?
Watts.
Ohmmeter.
Treat for physical shock.
48 ohms.

6. What voltage is required to force 5 amps through a 15-ohm resistor?
75 volts.
Stays the same.
Resistance.
A wire wound resistor.

7. How must two 12-volt batteries be connected in order to increase the current capacity?
Treat for physical shock.
6 volts.
In parallel.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

8. The most common reason that solid state devices fail is...
Heat
60 ohms.
It must prevent ignition of surrounding methane atmosphere.
It must prevent internal explosions.

9. What is the unit of electromotive force or electric pressure?
Voltage.
48 volts
4.8 ohms
Hydrogen.

10. The unit of measurement of current is...
Power.
200 volts
Amperes.
Higher current with voltage remaining the same.

11. How long should treatment for shock be continued?
Current.
Hydrogen.
Resistance.
Until the victim receives medical attention.

12. What voltage would be required to force 10 amps through a 50-ohm resistor?
Watts.
Stays the same.
500 volts.
Clean water.

13. What is the flow of electrons in a conductor?
Wattmeter.
Voltmeter.
8 ohms.
Current.

14. How many watts are in one horsepower?
746 watts.
Reverse.
Clean water.
Current.

15. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Soft iron.
A. Total resistance is less than the smallest resistor.
4.8 ohms
Series-wound.

16. The unit of measurement of resistance is?
Ohms.
No.4 AWG.
After charging
Power.

17. What is the total voltage of four 12-volt batteries connected in series?
Hydrogen.
In parallel.
48 volts
Treat for physical shock.

18. A triac is?
15 minutes.
A bi-directional device that can pass current in either direction.
Amperes.
Voltage.

19. Chemical burns caused by battery acid should be washed with clean water for at least...
A counter-EMF.
In series.
Higher current with voltage remaining the same.
15 minutes.

20. Unlike poles of a magnet will...
400 ampere-hours.
Attract each other.
96 volts.
6 volts.

21. Resistance is measured with a...
In parallel.
Ohmmeter.
4.0 ohms.
Better speed control on motors.

22. The combined resistance of two resistors in parallel is...
Less than the resistance of either resistor.
36 volts.
Burns will appear only at the point where contact is made to the energized circuit.
48 volts

23. Not true about electrical shocks?
48 ohms.
Compound-wound and shunt-wound.
Burns will appear only at the point where contact is made to the energized circuit.
No.4 AWG.

24. Batteries connected in parallel provide...
No.4 AWG.
Higher current with voltage remaining the same.
Voltage.
Decrease.

25. Power is measured with a...
Wattmeter.
Voltage.
48 ohms.
Watts.

26. Trailing cable on DC-powered mobile haulage equipment must be at least...
Until the victim receives medical attention.
Stays the same.
Flush thoroughly with water.
No.4 AWG.

27. 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...
After charging
Series-wound.
Treat for physical shock.
Amperes.

28. What is Ohm's Law?
The movement of electrons in a circuit.
E=IR.
Higher current with voltage remaining the same.
Burns will appear only at the point where contact is made to the energized circuit.

29. What should be used in treating an eye injury caused by battery acid?
Clean water.
It must prevent ignition of surrounding methane atmosphere.
Attract each other.
Less than the resistance of either resistor.

30. The core of an electro-magnet should be made of...
Soft iron.
Treat for physical shock.
100 ohms
No.4 AWG.

31. What must be provided at underground battery charging stations?
200 volts
Ventilation.
Stays the same.
It must prevent internal explosions.

32. The armature of a direct current motor - when running - generates...
No.4 AWG.
A counter-EMF.
Until the victim receives medical attention.
A wire wound resistor.

33. Storage battery charging stations must be provided with what kind of current protection?
6 volts.
Hydrometer.
Reverse.
Direct current.

34. Which of the following stays the same in all parts of a series circuit?
Ammeter.
It must prevent internal explosions.
Current
8 ohms.

35. What is the total resistance of four 25-ohm resistors connected in series?
Attract each other.
100 ohms
Current
No.4 AWG.

36. The best insulator against the lines of magnetic force is...
A counter-EMF.
Voltage.
Distance.
48 ohms.

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

38. The specific gravity of the electrolyte of a fully charged battery should be...
500 volts.
37.3 kilowatts
Hydrometer.
1.260 to 1.280.

39. Which of the following motors are considered to be constant or nearly constant speed?
Series-wound.
36 volts.
Compound-wound and shunt-wound.
Treat for physical shock.

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

41. Define current...
Current that flows in one direction only.
1.260 to 1.280.
The movement of electrons in a circuit.
100 ohms

42. What is the total voltage of four 9-volt batteries connected in a series?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
36 volts.
Wattmeter.
96 volts.

43. Voltage is measured with a...
500 volts.
Voltmeter.
48 volts
Ohmmeter.

44. If the cross-sectional area of a conductor is increased - its resistance will...
Series-wound.
Decrease.
96 volts.
Direct current.

45. The instrument used to check the electrolyte of a battery is a...
Clean water.
Hydrometer.
Voltmeter.
E=IR.

46. Define direct current...
Current
Repel each other.
Current that flows in one direction only.
Watts.

47. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Amperes.
Current
No.4 AWG.
Resistance.

48. What is the opposition to flow of electric current?
Voltage.
Resistance.
Voltmeter.
Direct current.

49. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
After charging
Watts.
No.4 AWG.

50. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
Decrease.
Current
Soft iron.