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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?
Distance.
96 volts.
1.260 to 1.280.
Until the victim receives medical attention.

2. How must two 12-volt batteries be connected in order to increase the current capacity?
Clean water.
In parallel.
100 ohms
Power.

3. Define direct current...
Current that flows in only one direction.
37.3 kilowatts
100 ohms
4.0 ohms.

4. What is the rate that work is done or heat is dissipated?
8 ohms.
4.8 ohms
Power.
Current that flows in one direction only.

5. Power is measured with a...
75 volts.
After charging
Wattmeter.
Amperes.

6. Unlike poles of a magnet will...
Attract each other.
Clean water.
Higher current with voltage remaining the same.
It must prevent ignition of surrounding methane atmosphere.

7. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
Direct current.
400 ampere-hours.
Power.

8. 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...
Flush thoroughly with water.
500 volts.
Treat for physical shock.
8 ohms.

9. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Hydrometer.
Flush thoroughly with water.
200 volts
4.0 ohms.

10. Which of the following motors are considered to be constant or nearly constant speed?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
48 volts
Compound-wound and shunt-wound.
A counter-EMF.

11. What is the total voltage of eight 12-volt batteries connected in series?
In series.
96 volts.
It must prevent internal explosions.
4.8 ohms

12. What is the total voltage of four 9-volt batteries connected in a series?
Better speed control on motors.
36 volts.
Power.
500 volts.

13. Which current flows in only one direction?
Voltmeter.
Clean water.
Compound-wound and shunt-wound.
Direct current.

14. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
4.0 ohms.
Hydrometer.
36 volts.
Stays the same.

15. The best insulator against the lines of magnetic force is...
Hydrometer.
It must prevent ignition of surrounding methane atmosphere.
Resistance.
Distance.

16. What is the total resistance of four 25-ohm resistors connected in series?
Flush thoroughly with water.
100 ohms
Attract each other.
In series.

17. Define current...
The movement of electrons in a circuit.
36 volts.
A counter-EMF.
Ohmmeter.

18. The longer the conductor - the greater the...
4.8 ohms
Resistance.
It must prevent internal explosions.
6 volts.

19. The core of an electro-magnet should be made of...
Ammeter.
Flush thoroughly with water.
Wattmeter.
Soft iron.

20. What should be used in treating an eye injury caused by battery acid?
8 ohms.
Clean water.
Current
Compound-wound and shunt-wound.

21. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
60 ohms.
Higher current with voltage remaining the same.
It must prevent ignition of surrounding methane atmosphere.
4.8 ohms

22. The explosive gas that is generated when a battery is charging is...
A bi-directional device that can pass current in either direction.
1.260 to 1.280.
Hydrogen.
In series.

23. Voltage in a parallel circuit...
Stays the same.
Hydrometer.
746 watts.
Current.

24. Define resistance...
In series.
36 volts.
The opposition to flow of electrons in a circuit.
It must prevent internal explosions.

25. Trailing cable on DC-powered mobile haulage equipment must be at least...
96 volts.
Better speed control on motors.
No.4 AWG.
Soft iron.

26. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Stays the same.
Ammeter.
Hydrogen.
Watts.

27. Resistance is measured with a...
A bi-directional device that can pass current in either direction.
Resistance.
Ohmmeter.
The movement of electrons in a circuit.

28. Batteries connected in parallel provide...
Soft iron.
A bi-directional device that can pass current in either direction.
It must prevent ignition of surrounding methane atmosphere.
Higher current with voltage remaining the same.

29. Resistors are rated in ohms and...
Compound-wound and shunt-wound.
Until the victim receives medical attention.
Watts.
A bi-directional device that can pass current in either direction.

30. The unit of measurement of current is...
In series.
Decrease.
Amperes.
Treat for physical shock.

31. What voltage would be required to force 10 amps through a 20-ohm resistor?
A wire wound resistor.
Current.
200 volts
Current that flows in one direction only.

32. Not an electro-magnet?
100 ohms
Flush the burn the clean water.
Ammeter.
A wire wound resistor.

33. Define direct current...
4.0 ohms.
Current that flows in one direction only.
In series.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

34. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
4.8 ohms
It must prevent internal explosions.
36 volts.

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

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36. In a parallel circuit...
Soft iron.
Amperes.
6 volts.
A. Total resistance is less than the smallest resistor.

37. The most common reason that solid state devices fail is...
48 volts
Heat
Flush thoroughly with water.
Voltage.

38. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Hydrogen.
96 volts.
Burns will appear only at the point where contact is made to the energized circuit.
In series.

39. Like poles of a magnet will...
The movement of electrons in a circuit.
Repel each other.
Distance.
Voltmeter.

40. What is the total resistance of three 16-ohm resistors connected in series?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Flush thoroughly with water.
Heat
48 ohms.

41. Which of the following stays the same in all parts of a series circuit?
48 volts
Direct current.
Hydrogen.
Current

42. What is Ohm's Law?
Resistance.
Ventilation.
60 ohms.
E=IR.

43. How many watts are in one horsepower?
746 watts.
Power.
No.4 AWG.
In series.

44. Which of the following is a requirement of an explosion-proof enclosure?
Ohms.
Distance.
In series.
It must prevent ignition of surrounding methane atmosphere.

45. What is the unit of electromotive force or electric pressure?
Voltage.
Resistance.
It must prevent ignition of surrounding methane atmosphere.
Current that flows in one direction only.

46. What is the total resistance of four 15-ohm resistors connected in series?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
60 ohms.
75 volts.
Direct current.

47. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
96 volts.
400 ampere-hours.
Current that flows in one direction only.
Compound-wound and shunt-wound.

48. The combined resistance of two resistors in parallel is...
Stays the same.
1.260 to 1.280.
Less than the resistance of either resistor.
Repel each other.

49. The unit of measurement of power is...
In series.
After charging
Current that flows in only one direction.
Watts.

50. Current in a series circuit...
Stays the same.
15 minutes.
In series.
Current