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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. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
Less than the resistance of either resistor.
Treat for physical shock.
Current.

2. The unit of measurement of power is...
Watts.
400 ampere-hours.
500 volts.
Direct current.

3. Resistance is measured with a...
Distance.
Reverse.
Ohmmeter.
Stays the same.

4. The unit of measurement of current is...
Ohmmeter.
Amperes.
Heat
Compound-wound and shunt-wound.

5. Current is measured with a (an)...
Ammeter.
Watts.
Resistance.
400 ampere-hours.

6. What is the rate that work is done or heat is dissipated?
Reverse.
Ammeter.
Heat
Power.

7. Resistors are rated in ohms and...
Voltage.
Stays the same.
Watts.
Ammeter.

8. Chemical burns caused by battery acid should be washed with clean water for at least...
The movement of electrons in a circuit.
15 minutes.
Current that flows in one direction only.
Ventilation.

9. How long should treatment for shock be continued?
15 minutes.
Compound-wound and shunt-wound.
It must prevent internal explosions.
Until the victim receives medical attention.

10. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Stays the same.
In series.
Until the victim receives medical attention.
Flush thoroughly with water.

11. The advantage of DC over AC is that DC offers...
Better speed control on motors.
In series.
Until the victim receives medical attention.
Reverse.

12. What is the total voltage of eight 12-volt batteries connected in series?
No.4 AWG.
96 volts.
Ventilation.
8 ohms.

13. What is Ohm's Law?
E=IR.
746 watts.
A counter-EMF.
Stays the same.

14. What is the unit of electromotive force or electric pressure?
In series.
Voltage.
Higher current with voltage remaining the same.
Current that flows in only one direction.

15. Not an electro-magnet?
Burns will appear only at the point where contact is made to the energized circuit.
A wire wound resistor.
Ammeter.
48 ohms.

16. The explosive gas that is generated when a battery is charging is...
746 watts.
200 volts
Ventilation.
Hydrogen.

17. The unit of measurement of resistance is?
48 ohms.
Flush thoroughly with water.
Ohms.
It must prevent ignition of surrounding methane atmosphere.

18. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
8 ohms.
Watts.
In series.

19. Batteries connected in parallel provide...
96 volts.
Ohmmeter.
Higher current with voltage remaining the same.
Ventilation.

20. What voltage is required to force 5 amps through a 15-ohm resistor?
96 volts.
In parallel.
100 ohms
75 volts.

21. What is the total resistance of three 16-ohm resistors connected in series?
Watts.
Until the victim receives medical attention.
Watts.
48 ohms.

22. The instrument used to check the electrolyte of a battery is a...
After charging
In series.
Hydrometer.
4.0 ohms.

23. What voltage would be required to force 10 amps through a 20-ohm resistor?
96 volts.
6 volts.
Resistance.
200 volts

24. Not a requirement of an explosion-proof enclosure?
Current
Stays the same.
It must prevent internal explosions.
200 volts

25. What is the total voltage of four 9-volt batteries connected in a series?
75 volts.
Resistance.
No.4 AWG.
36 volts.

26. How many watts are in one horsepower?
Current that flows in one direction only.
Direct current.
746 watts.
Repel each other.

27. Voltage is measured with a...
Voltmeter.
A counter-EMF.
Watts.
4.8 ohms

28. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Amperes.
36 volts.
Distance.
No.4 AWG.

29. 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...
Amperes.
Current that flows in one direction only.
Repel each other.
Treat for physical shock.

30. Like poles of a magnet will...
Repel each other.
Compound-wound and shunt-wound.
After charging
The movement of electrons in a circuit.

31. Define resistance...
200 volts
Ohms.
Stays the same.
The opposition to flow of electrons in a circuit.

32. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
Power.
Ohmmeter.
The opposition to flow of electrons in a circuit.

33. Power is measured with a...
Wattmeter.
96 volts.
48 ohms.
A counter-EMF.

34. What is the total voltage of four 12-volt batteries connected in series?
48 volts
4.8 ohms
Decrease.
37.3 kilowatts

35. How must two 12-volt batteries be connected in order to increase the current capacity?
No.4 AWG.
In parallel.
Watts.
Hydrometer.

36. The best insulator against the lines of magnetic force is...
E=IR.
400 ampere-hours.
Distance.
15 minutes.

37. The armature of a direct current motor - when running - generates...
The opposition to flow of electrons in a circuit.
Repel each other.
A counter-EMF.
Flush the burn the clean water.

38. Define current...
4.8 ohms
Burns will appear only at the point where contact is made to the energized circuit.
The movement of electrons in a circuit.
200 volts

39. If the cross-sectional area of a conductor is increased - its resistance will...
Decrease.
A. Total resistance is less than the smallest resistor.
Power.
Wattmeter.

40. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
In series.
Reverse.
Less than the resistance of either resistor.
4.8 ohms

41. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
Ammeter.
A bi-directional device that can pass current in either direction.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

42. The specific gravity of the electrolyte of a fully charged battery should be...
1.260 to 1.280.
Flush the burn the clean water.
In series.
In parallel.

43. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
4.8 ohms
Heat
A counter-EMF.
Resistance.

44. A triac is?
Current that flows in one direction only.
A bi-directional device that can pass current in either direction.
60 ohms.
8 ohms.

45. Which of the following motors CANNOT be run without a load?
After charging
Series-wound.
60 ohms.
Less than the resistance of either resistor.

46. Which of the following is a requirement of an explosion-proof enclosure?
500 volts.
8 ohms.
The movement of electrons in a circuit.
It must prevent ignition of surrounding methane atmosphere.

47. The longer the conductor - the greater the...
Resistance.
Voltmeter.
Decrease.
6 volts.

48. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Repel each other.
Ventilation.
1.260 to 1.280.
400 ampere-hours.

49. Voltage in a parallel circuit...
Higher current with voltage remaining the same.
Stays the same.
The movement of electrons in a circuit.
Wattmeter.

50. What is the total voltage of two 6-volt batteries connected in parallel?
Current that flows in one direction only.
After charging
6 volts.
Current that flows in only one direction.