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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. The longer the conductor - the greater the...
Resistance.
Current
75 volts.
Flush the burn the clean water.

2. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
200 volts
The opposition to flow of electrons in a circuit.
Treat for physical shock.
In series.

3. How must two 12-volt batteries be connected in order to increase the current capacity?
In parallel.
Stays the same.
400 ampere-hours.
Voltage.

4. What is Ohm's Law?
Voltmeter.
E=IR.
Stays the same.
Compound-wound and shunt-wound.

5. The unit of measurement of resistance is?
Treat for physical shock.
In series.
Hydrogen.
Ohms.

6. Current in a series circuit...
Stays the same.
Compound-wound and shunt-wound.
Series-wound.
Flush thoroughly with water.

7. What is the total voltage of two 6-volt batteries connected in parallel?
In parallel.
746 watts.
Flush thoroughly with water.
6 volts.

8. The explosive gas that is generated when a battery is charging is...
Soft iron.
746 watts.
Hydrogen.
200 volts

9. Define current...
Repel each other.
Hydrometer.
Ohms.
The movement of electrons in a circuit.

10. Resistors are rated in ohms and...
400 ampere-hours.
Watts.
36 volts.
A. Total resistance is less than the smallest resistor.

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

12. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Watts.
60 ohms.
In series.
Stays the same.

13. Which of the following is a requirement of an explosion-proof enclosure?
Attract each other.
Better speed control on motors.
It must prevent ignition of surrounding methane atmosphere.
Treat for physical shock.

14. Which of the following motors CANNOT be run without a load?
In parallel.
Less than the resistance of either resistor.
Series-wound.
Current that flows in one direction only.

15. The combined resistance of two resistors in parallel is...
Current
Hydrogen.
Less than the resistance of either resistor.
Current that flows in only one direction.

16. What voltage would be required to force 10 amps through a 20-ohm resistor?
200 volts
15 minutes.
Current
Wattmeter.

17. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
1.260 to 1.280.
Voltage.
75 volts.
4.8 ohms

18. Not true about electrical shocks?
Current that flows in only one direction.
A counter-EMF.
Burns will appear only at the point where contact is made to the energized circuit.
In series.

19. Not an electro-magnet?
A wire wound resistor.
Ohms.
Attract each other.
E=IR.

20. Resistance is measured with a...
Ohmmeter.
96 volts.
Ammeter.
Hydrometer.

21. What is the rate that work is done or heat is dissipated?
A. Total resistance is less than the smallest resistor.
Clean water.
Power.
Resistance.

22. What voltage is required to force 5 amps through a 15-ohm resistor?
75 volts.
Current.
In parallel.
The opposition to flow of electrons in a circuit.

23. When should water be added to a battery?
Ohms.
200 volts
After charging
Hydrogen.

24. Define resistance...
Voltmeter.
The opposition to flow of electrons in a circuit.
Current that flows in one direction only.
Stays the same.

25. What is the flow of electrons in a conductor?
Current.
Stays the same.
Hydrogen.
8 ohms.

26. 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
Treat for physical shock.
In series.
4.8 ohms

27. Which of the following stays the same in all parts of a series circuit?
Current
In series.
Ammeter.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

28. Define direct current...
Resistance.
A wire wound resistor.
Current that flows in one direction only.
Wattmeter.

29. Which of the following motors are considered to be constant or nearly constant speed?
A bi-directional device that can pass current in either direction.
Clean water.
Compound-wound and shunt-wound.
Heat

30. Unlike poles of a magnet will...
No.4 AWG.
Current.
Attract each other.
Reverse.

31. The armature of a direct current motor - when running - generates...
96 volts.
A counter-EMF.
Resistance.
Current that flows in one direction only.

32. How many kilowatts are used to develop 50 horsepower?
In parallel.
Watts.
Resistance.
37.3 kilowatts

33. How many watts are in one horsepower?
37.3 kilowatts
746 watts.
After charging
Resistance.

34. The core of an electro-magnet should be made of...
400 ampere-hours.
Soft iron.
Current
Watts.

35. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
Hydrometer.
A. Total resistance is less than the smallest resistor.
Voltage.
4.0 ohms.

36. Voltage in a parallel circuit...
Higher current with voltage remaining the same.
Stays the same.
15 minutes.
Less than the resistance of either resistor.

37. Storage battery charging stations must be provided with what kind of current protection?
No.4 AWG.
400 ampere-hours.
Reverse.
100 ohms

38. What voltage would be required to force 10 amps through a 50-ohm resistor?
In series.
Flush the burn the clean water.
500 volts.
A. Total resistance is less than the smallest resistor.

39. Current is measured with a (an)...
It must prevent ignition of surrounding methane atmosphere.
Repel each other.
96 volts.
Ammeter.

40. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Ohmmeter.
15 minutes.
A counter-EMF.
No.4 AWG.

41. The unit of measurement of power is...
A. Total resistance is less than the smallest resistor.
In series.
Watts.
Attract each other.

42. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Direct current.
E=IR.
400 ampere-hours.
The movement of electrons in a circuit.

43. What is the unit of electromotive force or electric pressure?
Higher current with voltage remaining the same.
Voltage.
Ventilation.
Ohms.

44. Define direct current...
6 volts.
Current that flows in only one direction.
A. Total resistance is less than the smallest resistor.
Repel each other.

45. The specific gravity of the electrolyte of a fully charged battery should be...
1.260 to 1.280.
Attract each other.
Amperes.
500 volts.

46. How long should treatment for shock be continued?
Higher current with voltage remaining the same.
96 volts.
Ohms.
Until the victim receives medical attention.

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

48. Power is measured with a...
Current
100 ohms
Wattmeter.
Treat for physical shock.

49. Chemical burns caused by battery acid should be washed with clean water for at least...
36 volts.
E=IR.
Direct current.
15 minutes.

50. Trailing cable on DC-powered mobile haulage equipment must be at least...
No.4 AWG.
8 ohms.
Clean water.
Hydrometer.