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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 instrument used to check the electrolyte of a battery is a...
Hydrogen.
Hydrometer.
After charging
Wattmeter.

2. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
E=IR.
Ventilation.
500 volts.

3. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Ohmmeter.
A wire wound resistor.
Stays the same.
400 ampere-hours.

4. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
36 volts.
Soft iron.
Hydrogen.

5. The longer the conductor - the greater the...
Hydrogen.
37.3 kilowatts
Resistance.
Hydrogen.

6. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Voltage.
No.4 AWG.
Hydrogen.
Hydrometer.

7. The best insulator against the lines of magnetic force is...
746 watts.
Current
Distance.
75 volts.

8. What should be used in treating an eye injury caused by battery acid?
Clean water.
Soft iron.
Current that flows in one direction only.
96 volts.

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

10. Batteries connected in parallel provide...
Burns will appear only at the point where contact is made to the energized circuit.
Higher current with voltage remaining the same.
It must prevent ignition of surrounding methane atmosphere.
Series-wound.

11. The unit of measurement of current is...
Ohmmeter.
500 volts.
4.8 ohms
Amperes.

12. What voltage would be required to force 10 amps through a 50-ohm resistor?
Watts.
500 volts.
Direct current.
Ohms.

13. Resistance is measured with a...
Treat for physical shock.
Ohmmeter.
Current.
In parallel.

14. Unlike poles of a magnet will...
Attract each other.
Heat
It must prevent ignition of surrounding methane atmosphere.
Better speed control on motors.

15. Trailing cable on DC-powered mobile haulage equipment must be at least...
A wire wound resistor.
E=IR.
No.4 AWG.
4.8 ohms

16. What must be provided at underground battery charging stations?
No.4 AWG.
Ventilation.
The opposition to flow of electrons in a circuit.
Ammeter.

17. The core of an electro-magnet should be made of...
Resistance.
Heat
4.0 ohms.
Soft iron.

18. Define direct current...
Flush the burn the clean water.
Current that flows in one direction only.
It must prevent ignition of surrounding methane atmosphere.
Distance.

19. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
Stays the same.
Flush the burn the clean water.
The movement of electrons in a circuit.

20. Current is measured with a (an)...
Stays the same.
In parallel.
Ammeter.
Burns will appear only at the point where contact is made to the energized circuit.

21. Which of the following stays the same in all parts of a series circuit?
Current
4.0 ohms.
Attract each other.
Ventilation.

22. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
In parallel.
In series.
746 watts.
Higher current with voltage remaining the same.

23. Which current flows in only one direction?
Stays the same.
200 volts
Higher current with voltage remaining the same.
Direct current.

24. What voltage would be required to force 10 amps through a 20-ohm resistor?
100 ohms
Decrease.
200 volts
Heat

25. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Burns will appear only at the point where contact is made to the energized circuit.
Power.
100 ohms
Flush thoroughly with water.

26. How long should treatment for shock be continued?
Until the victim receives medical attention.
Watts.
Treat for physical shock.
Power.

27. The unit of measurement of power is...
Watts.
Voltmeter.
No.4 AWG.
Distance.

28. The specific gravity of the electrolyte of a fully charged battery should be...
The movement of electrons in a circuit.
200 volts
746 watts.
1.260 to 1.280.

29. Which of the following motors CANNOT be run without a load?
Voltage.
Repel each other.
Series-wound.
48 volts

30. How many watts are in one horsepower?
Heat
Ohmmeter.
746 watts.
Treat for physical shock.

31. What is the total voltage of two 6-volt batteries connected in parallel?
Reverse.
Watts.
In series.
6 volts.

32. If the cross-sectional area of a conductor is increased - its resistance will...
The opposition to flow of electrons in a circuit.
Decrease.
1.260 to 1.280.
In series.

33. Not true about electrical shocks?
In series.
Burns will appear only at the point where contact is made to the energized circuit.
Higher current with voltage remaining the same.
Until the victim receives medical attention.

34. Resistors are rated in ohms and...
Ohmmeter.
Current.
Watts.
No.4 AWG.

35. Power is measured with a...
Amperes.
75 volts.
Soft iron.
Wattmeter.

36. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
Direct current.
Amperes.
Compound-wound and shunt-wound.
4.0 ohms.

37. Not a requirement of an explosion-proof enclosure?
It must prevent internal explosions.
Current that flows in one direction only.
Current.
Voltmeter.

38. What is the total voltage of four 9-volt batteries connected in a series?
Resistance.
36 volts.
Ohms.
4.0 ohms.

39. What is the first step in treating a chemical burn of the eye?
36 volts.
Compound-wound and shunt-wound.
Flush the burn the clean water.
In parallel.

40. What is the rate that work is done or heat is dissipated?
Series-wound.
Power.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
100 ohms

41. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
The opposition to flow of electrons in a circuit.
After charging
Voltage.
In series.

42. What is the unit of electromotive force or electric pressure?
Ohms.
Reverse.
Voltage.
The movement of electrons in a circuit.

43. Define current...
The movement of electrons in a circuit.
Current that flows in one direction only.
200 volts
Less than the resistance of either resistor.

44. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
4.8 ohms
746 watts.
Direct current.
6 volts.

45. The armature of a direct current motor - when running - generates...
A counter-EMF.
After charging
The opposition to flow of electrons in a circuit.
Stays the same.

46. The advantage of DC over AC is that DC offers...
Watts.
Hydrometer.
Better speed control on motors.
Burns will appear only at the point where contact is made to the energized circuit.

47. What is Ohm's Law?
48 ohms.
Resistance.
E=IR.
Repel each other.

48. Chemical burns caused by battery acid should be washed with clean water for at least...
100 ohms
Power.
Attract each other.
15 minutes.

49. What is the total resistance of four 15-ohm resistors connected in series?
60 ohms.
4.0 ohms.
A. Total resistance is less than the smallest resistor.
Until the victim receives medical attention.

50. 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'.
Watts.
8 ohms.
Less than the resistance of either resistor.