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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 must be provided at underground battery charging stations?
The movement of electrons in a circuit.
Amperes.
Ventilation.
Burns will appear only at the point where contact is made to the energized circuit.

2. Resistors are rated in ohms and...
400 ampere-hours.
Watts.
Hydrometer.
Current.

3. What is the first step in treating a chemical burn of the eye?
Flush the burn the clean water.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Reverse.
Stays the same.

4. The combined resistance of two resistors in parallel is...
It must prevent ignition of surrounding methane atmosphere.
48 ohms.
Less than the resistance of either resistor.
Repel each other.

5. Define direct current...
Current that flows in one direction only.
15 minutes.
E=IR.
48 ohms.

6. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
8 ohms.
Watts.
500 volts.
Until the victim receives medical attention.

7. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
500 volts.
Power.
Heat
4.8 ohms

8. What is the flow of electrons in a conductor?
Current.
4.0 ohms.
Hydrogen.
15 minutes.

9. The advantage of DC over AC is that DC offers...
Better speed control on motors.
746 watts.
Compound-wound and shunt-wound.
Hydrometer.

10. Not true about electrical shocks?
The movement of electrons in a circuit.
Less than the resistance of either resistor.
Burns will appear only at the point where contact is made to the energized circuit.
Resistance.

11. Define direct current...
Better speed control on motors.
Current that flows in only one direction.
96 volts.
60 ohms.

12. Define resistance...
The opposition to flow of electrons in a circuit.
Resistance.
Ventilation.
Direct current.

13. Like poles of a magnet will...
It must prevent internal explosions.
Repel each other.
Ohmmeter.
Burns will appear only at the point where contact is made to the energized circuit.

14. The most common reason that solid state devices fail is...
Heat
In series.
Voltage.
36 volts.

15. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
4.8 ohms
A wire wound resistor.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

16. Voltage is measured with a...
96 volts.
Until the victim receives medical attention.
Voltmeter.
Watts.

17. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Wattmeter.
Higher current with voltage remaining the same.
Resistance.
No.4 AWG.

18. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
Flush the burn the clean water.
Clean water.
Stays the same.

19. What is the total voltage of two 6-volt batteries connected in parallel?
A. Total resistance is less than the smallest resistor.
6 volts.
Better speed control on motors.
Treat for physical shock.

20. Current is measured with a (an)...
Reverse.
Wattmeter.
Stays the same.
Ammeter.

21. How must two 12-volt batteries be connected in order to increase the current capacity?
48 ohms.
No.4 AWG.
In parallel.
75 volts.

22. Trailing cable on DC-powered mobile haulage equipment must be at least...
Current
After charging
No.4 AWG.
A counter-EMF.

23. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Hydrogen.
Resistance.
Direct current.
Distance.

24. What is the total voltage of four 12-volt batteries connected in series?
36 volts.
48 volts
The opposition to flow of electrons in a circuit.
1.260 to 1.280.

25. Batteries connected in parallel provide...
200 volts
4.8 ohms
In parallel.
Higher current with voltage remaining the same.

26. How many kilowatts are used to develop 50 horsepower?
Until the victim receives medical attention.
37.3 kilowatts
Resistance.
1.260 to 1.280.

27. Unlike poles of a magnet will...
37.3 kilowatts
48 volts
48 ohms.
Attract each other.

28. In a parallel circuit...
Higher current with voltage remaining the same.
A. Total resistance is less than the smallest resistor.
37.3 kilowatts
It must prevent ignition of surrounding methane atmosphere.

29. What is the total voltage of four 9-volt batteries connected in a series?
96 volts.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
36 volts.
Compound-wound and shunt-wound.

30. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Flush thoroughly with water.
Heat
In series.
Attract each other.

31. The unit of measurement of current is...
Ammeter.
4.8 ohms
No.4 AWG.
Amperes.

32. What is the unit of electromotive force or electric pressure?
Power.
Voltage.
Ammeter.
8 ohms.

33. The longer the conductor - the greater the...
Wattmeter.
Resistance.
Burns will appear only at the point where contact is made to the energized circuit.
Repel each other.

34. How long should treatment for shock be continued?
Until the victim receives medical attention.
Ohmmeter.
400 ampere-hours.
Current that flows in one direction only.

35. A triac is?
Stays the same.
A bi-directional device that can pass current in either direction.
Direct current.
36 volts.

36. What is Ohm's Law?
E=IR.
100 ohms
Flush thoroughly with water.
Current.

37. What should be used in treating an eye injury caused by battery acid?
A. Total resistance is less than the smallest resistor.
The opposition to flow of electrons in a circuit.
Clean water.
Decrease.

38. The unit of measurement of power is...
Watts.
Ventilation.
746 watts.
A counter-EMF.

39. What voltage would be required to force 10 amps through a 50-ohm resistor?
Ohms.
500 volts.
Current that flows in one direction only.
A wire wound resistor.

40. The armature of a direct current motor - when running - generates...
E=IR.
A counter-EMF.
Ohmmeter.
Repel each other.

41. The specific gravity of the electrolyte of a fully charged battery should be...
Decrease.
A wire wound resistor.
1.260 to 1.280.
500 volts.

42. Current in a series circuit...
Flush the burn the clean water.
Stays the same.
Wattmeter.
Compound-wound and shunt-wound.

43. Resistance is measured with a...
Clean water.
36 volts.
400 ampere-hours.
Ohmmeter.

44. 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...
Treat for physical shock.
Burns will appear only at the point where contact is made to the energized circuit.
500 volts.
It must prevent internal explosions.

45. When should water be added to a battery?
48 volts
Soft iron.
After charging
Current that flows in one direction only.

46. The unit of measurement of resistance is?
Voltage.
Voltmeter.
Ohms.
Hydrogen.

47. How many watts are in one horsepower?
37.3 kilowatts
Resistance.
Current that flows in one direction only.
746 watts.

48. What voltage would be required to force 10 amps through a 20-ohm resistor?
Better speed control on motors.
200 volts
E=IR.
Ohms.

49. What is the rate that work is done or heat is dissipated?
Power.
1.260 to 1.280.
Resistance.
Hydrogen.

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

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