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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?
Until the victim receives medical attention.
100 ohms
Flush thoroughly with water.
Ventilation.

2. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Resistance.
In series.
36 volts.
It must prevent internal explosions.

3. Storage battery charging stations must be provided with what kind of current protection?
Ohms.
500 volts.
Reverse.
Current that flows in one direction only.

4. Define current...
The movement of electrons in a circuit.
E=IR.
200 volts
Soft iron.

5. What is the total voltage of four 12-volt batteries connected in series?
Burns will appear only at the point where contact is made to the energized circuit.
A. Total resistance is less than the smallest resistor.
48 volts
Voltage.

6. Batteries connected in parallel provide...
Current
Higher current with voltage remaining the same.
In series.
Current that flows in only one direction.

7. Resistance is measured with a...
Watts.
Ohmmeter.
Reverse.
After charging

8. What voltage is required to force 5 amps through a 15-ohm resistor?
Resistance.
Treat for physical shock.
75 volts.
Distance.

9. Unlike poles of a magnet will...
Repel each other.
Attract each other.
96 volts.
The movement of electrons in a circuit.

10. The longer the conductor - the greater the...
Resistance.
Less than the resistance of either resistor.
Better speed control on motors.
Hydrogen.

11. A triac is?
Higher current with voltage remaining the same.
A bi-directional device that can pass current in either direction.
96 volts.
Clean water.

12. Resistors are rated in ohms and...
The opposition to flow of electrons in a circuit.
400 ampere-hours.
Until the victim receives medical attention.
Watts.

13. What is the rate that work is done or heat is dissipated?
Series-wound.
Current that flows in one direction only.
Power.
Ventilation.

14. Not true about electrical shocks?
Burns will appear only at the point where contact is made to the energized circuit.
Until the victim receives medical attention.
Hydrogen.
Ammeter.

15. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
75 volts.
48 ohms.
Voltage.

16. Voltage is measured with a...
37.3 kilowatts
Hydrometer.
Voltmeter.
Less than the resistance of either resistor.

17. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
36 volts.
No.4 AWG.
Amperes.

18. Which of the following motors CANNOT be run without a load?
A bi-directional device that can pass current in either direction.
A wire wound resistor.
Series-wound.
Stays the same.

19. If the cross-sectional area of a conductor is increased - its resistance will...
Watts.
Clean water.
Decrease.
Treat for physical shock.

20. What must be provided at underground battery charging stations?
A wire wound resistor.
Until the victim receives medical attention.
Ventilation.
Treat for physical shock.

21. The advantage of DC over AC is that DC offers...
Watts.
Series-wound.
Better speed control on motors.
Stays the same.

22. Voltage in a parallel circuit...
Voltmeter.
8 ohms.
Stays the same.
75 volts.

23. What voltage would be required to force 10 amps through a 50-ohm resistor?
75 volts.
500 volts.
100 ohms
Distance.

24. Define direct current...
In series.
Current that flows in only one direction.
48 volts
Repel each other.

25. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
In parallel.
Compound-wound and shunt-wound.
75 volts.
4.0 ohms.

26. Current in a series circuit...
Less than the resistance of either resistor.
A counter-EMF.
75 volts.
Stays the same.

27. The most common reason that solid state devices fail is...
Flush the burn the clean water.
Voltmeter.
Direct current.
Heat

28. The combined resistance of two resistors in parallel is...
It must prevent ignition of surrounding methane atmosphere.
400 ampere-hours.
It must prevent internal explosions.
Less than the resistance of either resistor.

29. The explosive gas that is generated when a battery is charging is...
6 volts.
Hydrogen.
In series.
Flush thoroughly with water.

30. What is the unit of electromotive force or electric pressure?
200 volts
Watts.
Hydrogen.
Voltage.

31. The instrument used to check the electrolyte of a battery is a...
4.0 ohms.
4.8 ohms
36 volts.
Hydrometer.

32. Not a requirement of an explosion-proof enclosure?
In parallel.
A wire wound resistor.
No.4 AWG.
It must prevent internal explosions.

33. What is the total resistance of four 15-ohm resistors connected in series?
A bi-directional device that can pass current in either direction.
Resistance.
96 volts.
60 ohms.

34. Which of the following is a requirement of an explosion-proof enclosure?
400 ampere-hours.
It must prevent ignition of surrounding methane atmosphere.
Series-wound.
Voltmeter.

35. What is the total voltage of four 9-volt batteries connected in a series?
No.4 AWG.
15 minutes.
Direct current.
36 volts.

36. Trailing cable on DC-powered mobile haulage equipment must be at least...
Decrease.
No.4 AWG.
Ammeter.
Wattmeter.

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

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38. What should be used in treating an eye injury caused by battery acid?
Clean water.
Current.
Soft iron.
96 volts.

39. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
In series.
Direct current.
400 ampere-hours.
Voltage.

40. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Attract each other.
48 volts
No.4 AWG.
Power.

41. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Hydrogen.
Flush thoroughly with water.
Ventilation.
15 minutes.

42. Like poles of a magnet will...
In series.
Repel each other.
E=IR.
Stays the same.

43. The unit of measurement of current is...
8 ohms.
Ammeter.
Amperes.
Ohmmeter.

44. The unit of measurement of power is...
Soft iron.
Repel each other.
Watts.
746 watts.

45. What is the total resistance of three 16-ohm resistors connected in series?
36 volts.
A wire wound resistor.
48 ohms.
Until the victim receives medical attention.

46. What is the total resistance of four 25-ohm resistors connected in series?
100 ohms
Clean water.
E=IR.
36 volts.

47. Which of the following motors are considered to be constant or nearly constant speed?
Resistance.
Burns will appear only at the point where contact is made to the energized circuit.
Ohmmeter.
Compound-wound and shunt-wound.

48. How many watts are in one horsepower?
746 watts.
Ohms.
500 volts.
Treat for physical shock.

49. What is the first step in treating a chemical burn of the eye?
Until the victim receives medical attention.
Distance.
Direct current.
Flush the burn the clean water.

50. When should water be added to a battery?
In series.
Better speed control on motors.
After charging
Power.