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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. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Better speed control on motors.
400 ampere-hours.
Resistance.
Ammeter.

2. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Resistance.
Flush thoroughly with water.
37.3 kilowatts
15 minutes.

3. Power is measured with a...
Wattmeter.
48 volts
In series.
36 volts.

4. Define direct current...
Attract each other.
Power.
Ammeter.
Current that flows in only one direction.

5. Current in a series circuit...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Amperes.
Stays the same.
500 volts.

6. Not an electro-magnet?
Clean water.
Repel each other.
A wire wound resistor.
No.4 AWG.

7. The specific gravity of the electrolyte of a fully charged battery should be...
Flush thoroughly with water.
E=IR.
Flush the burn the clean water.
1.260 to 1.280.

8. How many watts are in one horsepower?
Decrease.
Current.
746 watts.
Watts.

9. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
Less than the resistance of either resistor.
A wire wound resistor.
Power.

10. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
500 volts.
In series.
Resistance.
Higher current with voltage remaining the same.

11. How must two 12-volt batteries be connected in order to increase the current capacity?
Current.
Heat
In parallel.
Current that flows in one direction only.

12. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Compound-wound and shunt-wound.
75 volts.
No.4 AWG.
After charging

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

14. What is the total voltage of eight 12-volt batteries connected in series?
Compound-wound and shunt-wound.
Current.
96 volts.
Hydrogen.

15. What is the total resistance of four 25-ohm resistors connected in series?
In parallel.
100 ohms
Wattmeter.
15 minutes.

16. Not true about electrical shocks?
Reverse.
Ohmmeter.
A wire wound resistor.
Burns will appear only at the point where contact is made to the energized circuit.

17. The core of an electro-magnet should be made of...
100 ohms
Soft iron.
Clean water.
Attract each other.

18. The unit of measurement of current is...
1.260 to 1.280.
400 ampere-hours.
E=IR.
Amperes.

19. What voltage would be required to force 10 amps through a 20-ohm resistor?
200 volts
Less than the resistance of either resistor.
Current that flows in only one direction.
Flush the burn the clean water.

20. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
Power.
Voltage.
It must prevent ignition of surrounding methane atmosphere.

21. The advantage of DC over AC is that DC offers...
Decrease.
Better speed control on motors.
Hydrogen.
1.260 to 1.280.

22. If the cross-sectional area of a conductor is increased - its resistance will...
Hydrogen.
Decrease.
Attract each other.
Repel each other.

23. Like poles of a magnet will...
No.4 AWG.
48 ohms.
Repel each other.
A bi-directional device that can pass current in either direction.

24. The armature of a direct current motor - when running - generates...
Resistance.
200 volts
Amperes.
A counter-EMF.

25. What should be used in treating an eye injury caused by battery acid?
Treat for physical shock.
Clean water.
Higher current with voltage remaining the same.
Distance.

26. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
Less than the resistance of either resistor.
A wire wound resistor.
Current

27. What is the first step in treating a chemical burn of the eye?
100 ohms
Flush the burn the clean water.
Voltage.
1.260 to 1.280.

28. Unlike poles of a magnet will...
746 watts.
Attract each other.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Current that flows in one direction only.

29. What is the unit of electromotive force or electric pressure?
Voltage.
E=IR.
Ammeter.
Hydrogen.

30. The most common reason that solid state devices fail is...
The movement of electrons in a circuit.
Heat
Watts.
200 volts

31. The longer the conductor - the greater the...
Current that flows in one direction only.
Resistance.
Flush thoroughly with water.
4.0 ohms.

32. A triac is?
Treat for physical shock.
Burns will appear only at the point where contact is made to the energized circuit.
In series.
A bi-directional device that can pass current in either direction.

33. What is the flow of electrons in a conductor?
Power.
Flush thoroughly with water.
Current.
500 volts.

34. Resistors are rated in ohms and...
Watts.
Better speed control on motors.
Reverse.
Ammeter.

35. Batteries connected in parallel provide...
8 ohms.
Higher current with voltage remaining the same.
500 volts.
A. Total resistance is less than the smallest resistor.

36. Define current...
48 ohms.
200 volts
400 ampere-hours.
The movement of electrons in a circuit.

37. Which of the following stays the same in all parts of a series circuit?
Repel each other.
Power.
Current
100 ohms

38. Define resistance...
Repel each other.
Soft iron.
The movement of electrons in a circuit.
The opposition to flow of electrons in a circuit.

39. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Hydrometer.
Hydrogen.
Attract each other.
1.260 to 1.280.

40. Voltage in a parallel circuit...
A wire wound resistor.
Stays the same.
A. Total resistance is less than the smallest resistor.
A bi-directional device that can pass current in either direction.

41. Resistance is measured with a...
Ohmmeter.
Repel each other.
Stays the same.
Ventilation.

42. The best insulator against the lines of magnetic force is...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Distance.
Compound-wound and shunt-wound.
36 volts.

43. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
96 volts.
400 ampere-hours.
4.0 ohms.
Treat for physical shock.

44. The unit of measurement of power is...
15 minutes.
Flush thoroughly with water.
Watts.
8 ohms.

45. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
37.3 kilowatts
4.0 ohms.
4.8 ohms
60 ohms.

46. What must be provided at underground battery charging stations?
Power.
Decrease.
Ventilation.
15 minutes.

47. What is the total voltage of four 9-volt batteries connected in a series?
36 volts.
In series.
Better speed control on motors.
Until the victim receives medical attention.

48. How long should treatment for shock be continued?
36 volts.
Until the victim receives medical attention.
8 ohms.
E=IR.

49. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
60 ohms.
Ohmmeter.
Hydrometer.

50. 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...
Watts.
Treat for physical shock.
Distance.
200 volts