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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. What is the unit of electromotive force or electric pressure?
6 volts.
Voltage.
Resistance.
8 ohms.

2. The specific gravity of the electrolyte of a fully charged battery should be...
Voltage.
1.260 to 1.280.
It must prevent internal explosions.
The movement of electrons in a circuit.

3. Storage battery charging stations must be provided with what kind of current protection?
It must prevent internal explosions.
Reverse.
In series.
Decrease.

4. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
No.4 AWG.
Heat
Hydrogen.
In series.

5. Define direct current...
Voltage.
Current that flows in one direction only.
Until the victim receives medical attention.
The opposition to flow of electrons in a circuit.

6. Current in a series circuit...
Stays the same.
In parallel.
96 volts.
500 volts.

7. Define direct current...
Current that flows in only one direction.
Current
Better speed control on motors.
15 minutes.

8. What must be provided at underground battery charging stations?
A wire wound resistor.
Ventilation.
Series-wound.
Ohmmeter.

9. Chemical burns caused by battery acid should be washed with clean water for at least...
It must prevent internal explosions.
6 volts.
Stays the same.
15 minutes.

10. What is the total voltage of eight 12-volt batteries connected in series?
96 volts.
Flush thoroughly with water.
Hydrometer.
48 ohms.

11. What is Ohm's Law?
Amperes.
Decrease.
Voltmeter.
E=IR.

12. The unit of measurement of current is...
200 volts
37.3 kilowatts
Amperes.
Watts.

13. Like poles of a magnet will...
Repel each other.
Heat
15 minutes.
75 volts.

14. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
Repel each other.
Distance.
The movement of electrons in a circuit.
4.0 ohms.

15. The advantage of DC over AC is that DC offers...
Better speed control on motors.
Reverse.
E=IR.
In series.

16. What is the flow of electrons in a conductor?
Current
4.8 ohms
Current.
500 volts.

17. The longer the conductor - the greater the...
Resistance.
The movement of electrons in a circuit.
E=IR.
36 volts.

18. Voltage in a parallel circuit...
Stays the same.
Current
1.260 to 1.280.
Reverse.

19. What voltage would be required to force 10 amps through a 20-ohm resistor?
200 volts
Hydrometer.
Soft iron.
1.260 to 1.280.

20. What is the total voltage of four 9-volt batteries connected in a series?
Compound-wound and shunt-wound.
E=IR.
36 volts.
Watts.

21. The instrument used to check the electrolyte of a battery is a...
Hydrometer.
100 ohms
36 volts.
E=IR.

22. Which of the following motors are considered to be constant or nearly constant speed?
48 ohms.
Distance.
75 volts.
Compound-wound and shunt-wound.

23. How long should treatment for shock be continued?
Current that flows in only one direction.
Until the victim receives medical attention.
Current
Stays the same.

24. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
No.4 AWG.
Current.
400 ampere-hours.
Watts.

25. What is the total resistance of four 15-ohm resistors connected in series?
It must prevent ignition of surrounding methane atmosphere.
60 ohms.
Ohmmeter.
In series.

26. Batteries connected in parallel provide...
Hydrogen.
Decrease.
Higher current with voltage remaining the same.
Stays the same.

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...
Current that flows in one direction only.
No.4 AWG.
Treat for physical shock.
E=IR.

28. Trailing cable on DC-powered mobile haulage equipment must be at least...
Reverse.
Resistance.
Power.
No.4 AWG.

29. A triac is?
Ammeter.
96 volts.
Resistance.
A bi-directional device that can pass current in either direction.

30. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
400 ampere-hours.
Burns will appear only at the point where contact is made to the energized circuit.
96 volts.
Resistance.

31. The best insulator against the lines of magnetic force is...
Compound-wound and shunt-wound.
Stays the same.
Distance.
36 volts.

32. How many kilowatts are used to develop 50 horsepower?
Current
Hydrometer.
37.3 kilowatts
Attract each other.

33. Which current flows in only one direction?
Direct current.
E=IR.
8 ohms.
Repel each other.

34. Not a requirement of an explosion-proof enclosure?
Current.
4.0 ohms.
It must prevent internal explosions.
100 ohms

35. Define current...
Attract each other.
Flush the burn the clean water.
8 ohms.
The movement of electrons in a circuit.

36. How must two 12-volt batteries be connected in order to increase the current capacity?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
In parallel.
Ohms.
Watts.

37. What is the opposition to flow of electric current?
In parallel.
Flush the burn the clean water.
Resistance.
Flush thoroughly with water.

38. How many watts are in one horsepower?
746 watts.
A wire wound resistor.
Attract each other.
4.8 ohms

39. The most common reason that solid state devices fail is...
48 ohms.
No.4 AWG.
After charging
Heat

40. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
It must prevent internal explosions.
Resistance.
No.4 AWG.

41. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Direct current.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Flush thoroughly with water.
75 volts.

42. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
8 ohms.
Stays the same.
Current that flows in only one direction.
Flush the burn the clean water.

43. The core of an electro-magnet should be made of...
Soft iron.
A wire wound resistor.
Current that flows in one direction only.
Flush thoroughly with water.

44. Not true about electrical shocks?
Burns will appear only at the point where contact is made to the energized circuit.
4.0 ohms.
Power.
Better speed control on motors.

45. The unit of measurement of power is...
Stays the same.
4.8 ohms
96 volts.
Watts.

46. What is the total voltage of four 12-volt batteries connected in series?
48 volts
Flush the burn the clean water.
Resistance.
1.260 to 1.280.

47. Which of the following is a requirement of an explosion-proof enclosure?
Less than the resistance of either resistor.
It must prevent ignition of surrounding methane atmosphere.
Better speed control on motors.
Soft iron.

48. Voltage is measured with a...
It must prevent internal explosions.
Voltmeter.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
37.3 kilowatts

49. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Less than the resistance of either resistor.
Resistance.
Hydrogen.
Current

50. Not an electro-magnet?
The movement of electrons in a circuit.
Series-wound.
Amperes.
A wire wound resistor.