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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 is measured with a (an)...
Decrease.
Watts.
Current that flows in only one direction.
Ammeter.

2. The advantage of DC over AC is that DC offers...
Current
In series.
It must prevent internal explosions.
Better speed control on motors.

3. Which of the following stays the same in all parts of a series circuit?
A counter-EMF.
Hydrometer.
Current
Ventilation.

4. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
4.0 ohms.
Wattmeter.
4.8 ohms
Ohmmeter.

5. What is the total voltage of eight 12-volt batteries connected in series?
Burns will appear only at the point where contact is made to the energized circuit.
48 volts
Reverse.
96 volts.

6. Voltage in a parallel circuit...
Flush thoroughly with water.
Resistance.
Distance.
Stays the same.

7. The explosive gas that is generated when a battery is charging is...
Ventilation.
Ohms.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Hydrogen.

8. Define resistance...
Heat
Soft iron.
The opposition to flow of electrons in a circuit.
Voltage.

9. If the cross-sectional area of a conductor is increased - its resistance will...
Voltage.
Decrease.
Ammeter.
500 volts.

10. The best insulator against the lines of magnetic force is...
Current
A bi-directional device that can pass current in either direction.
Distance.
In series.

11. The unit of measurement of current is...
Current that flows in only one direction.
Amperes.
Hydrogen.
Power.

12. What is the total voltage of two 6-volt batteries connected in parallel?
Ammeter.
6 volts.
In series.
96 volts.

13. The first step in treating a chemical burn - such as one caused by battery acid - is to...
36 volts.
Current
Flush thoroughly with water.
15 minutes.

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

15. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
No.4 AWG.
400 ampere-hours.
Series-wound.
Ammeter.

16. Which current flows in only one direction?
A bi-directional device that can pass current in either direction.
Burns will appear only at the point where contact is made to the energized circuit.
Direct current.
Stays the same.

17. What is the first step in treating a chemical burn of the eye?
Flush the burn the clean water.
Resistance.
Current.
6 volts.

18. What is the rate that work is done or heat is dissipated?
Resistance.
Better speed control on motors.
Power.
Current.

19. Which of the following motors CANNOT be run without a load?
Resistance.
Decrease.
36 volts.
Series-wound.

20. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
Hydrometer.
Better speed control on motors.
In parallel.

21. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
1.260 to 1.280.
Current
In series.
Power.

22. Unlike poles of a magnet will...
Attract each other.
Hydrogen.
Ventilation.
Soft iron.

23. A triac is?
Higher current with voltage remaining the same.
Soft iron.
A. Total resistance is less than the smallest resistor.
A bi-directional device that can pass current in either direction.

24. What is the unit of electromotive force or electric pressure?
Voltage.
500 volts.
8 ohms.
Attract each other.

25. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
8 ohms.
Voltage.
48 volts
Resistance.

26. Like poles of a magnet will...
A. Total resistance is less than the smallest resistor.
Repel each other.
75 volts.
Until the victim receives medical attention.

27. How many watts are in one horsepower?
It must prevent internal explosions.
Attract each other.
746 watts.
4.8 ohms

28. How must two 12-volt batteries be connected in order to increase the current capacity?
Power.
In series.
In parallel.
36 volts.

29. Define direct current...
Power.
Current that flows in one direction only.
It must prevent internal explosions.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

30. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
Hydrometer.
Ventilation.
Amperes.

31. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Treat for physical shock.
It must prevent internal explosions.
In series.
Stays the same.

32. What is Ohm's Law?
Attract each other.
75 volts.
E=IR.
In series.

33. Voltage is measured with a...
Watts.
Voltmeter.
In series.
100 ohms

34. The unit of measurement of resistance is?
Burns will appear only at the point where contact is made to the energized circuit.
Higher current with voltage remaining the same.
Ohmmeter.
Ohms.

35. What is the total resistance of three 16-ohm resistors connected in series?
Ammeter.
48 ohms.
Series-wound.
200 volts

36. How long should treatment for shock be continued?
Watts.
Wattmeter.
Until the victim receives medical attention.
Soft iron.

37. Not an electro-magnet?
A wire wound resistor.
A counter-EMF.
Stays the same.
Repel each other.

38. What must be provided at underground battery charging stations?
No.4 AWG.
Amperes.
746 watts.
Ventilation.

39. Not a requirement of an explosion-proof enclosure?
6 volts.
48 ohms.
It must prevent internal explosions.
8 ohms.

40. What is the flow of electrons in a conductor?
Ohms.
Heat
Until the victim receives medical attention.
Current.

41. What voltage would be required to force 10 amps through a 20-ohm resistor?
In parallel.
200 volts
8 ohms.
60 ohms.

42. 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...
Repel each other.
Voltmeter.
Treat for physical shock.
1.260 to 1.280.

43. Define direct current...
75 volts.
746 watts.
A counter-EMF.
Current that flows in only one direction.

44. What is the total resistance of four 15-ohm resistors connected in series?
The opposition to flow of electrons in a circuit.
60 ohms.
A counter-EMF.
Hydrometer.

45. When should water be added to a battery?
After charging
Flush the burn the clean water.
4.8 ohms
It must prevent ignition of surrounding methane atmosphere.

46. The instrument used to check the electrolyte of a battery is a...
Current that flows in only one direction.
Soft iron.
Watts.
Hydrometer.

47. Resistance is measured with a...
Hydrogen.
In series.
Ohmmeter.
Current.

48. The armature of a direct current motor - when running - generates...
A counter-EMF.
48 volts
E=IR.
Power.

49. What voltage is required to force 5 amps through a 15-ohm resistor?
60 ohms.
Flush the burn the clean water.
Direct current.
75 volts.

50. The specific gravity of the electrolyte of a fully charged battery should be...
1.260 to 1.280.
48 ohms.
Current that flows in only one direction.
Attract each other.