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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. Resistors are rated in ohms and...
8 ohms.
Burns will appear only at the point where contact is made to the energized circuit.
Repel each other.
Watts.

2. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
Better speed control on motors.
200 volts
Resistance.

3. Storage battery charging stations must be provided with what kind of current protection?
Distance.
Ammeter.
Reverse.
A bi-directional device that can pass current in either direction.

4. Batteries connected in parallel provide...
Higher current with voltage remaining the same.
6 volts.
200 volts
Hydrogen.

5. Define current...
Compound-wound and shunt-wound.
Ohms.
In parallel.
The movement of electrons in a circuit.

6. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
Hydrogen.
A wire wound resistor.
The movement of electrons in a circuit.

7. Like poles of a magnet will...
Treat for physical shock.
The movement of electrons in a circuit.
96 volts.
Repel each other.

8. If the cross-sectional area of a conductor is increased - its resistance will...
Voltage.
Treat for physical shock.
Decrease.
Series-wound.

9. Voltage in a parallel circuit...
It must prevent ignition of surrounding methane atmosphere.
Stays the same.
Less than the resistance of either resistor.
A bi-directional device that can pass current in either direction.

10. Current in a series circuit...
Stays the same.
A. Total resistance is less than the smallest resistor.
Less than the resistance of either resistor.
96 volts.

11. What is the total voltage of four 9-volt batteries connected in a series?
Wattmeter.
Ammeter.
Clean water.
36 volts.

12. Current is measured with a (an)...
Ammeter.
It must prevent ignition of surrounding methane atmosphere.
E=IR.
4.8 ohms

13. The instrument used to check the electrolyte of a battery is a...
15 minutes.
Less than the resistance of either resistor.
Hydrometer.
Attract each other.

14. The advantage of DC over AC is that DC offers...
Series-wound.
48 ohms.
Better speed control on motors.
75 volts.

15. Define direct current...
200 volts
Current that flows in one direction only.
Better speed control on motors.
After charging

16. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Less than the resistance of either resistor.
In series.
Power.
75 volts.

17. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Resistance.
8 ohms.
Repel each other.
Watts.

18. Power is measured with a...
It must prevent ignition of surrounding methane atmosphere.
Wattmeter.
Series-wound.
Voltage.

19. Define resistance...
Current that flows in only one direction.
The opposition to flow of electrons in a circuit.
Reverse.
Ammeter.

20. The unit of measurement of resistance is?
Watts.
No.4 AWG.
37.3 kilowatts
Ohms.

21. The unit of measurement of current is...
Amperes.
Hydrometer.
Voltmeter.
96 volts.

22. The explosive gas that is generated when a battery is charging is...
8 ohms.
The movement of electrons in a circuit.
Higher current with voltage remaining the same.
Hydrogen.

23. The most common reason that solid state devices fail is...
75 volts.
A bi-directional device that can pass current in either direction.
The opposition to flow of electrons in a circuit.
Heat

24. Which of the following stays the same in all parts of a series circuit?
Soft iron.
Current
Current.
4.0 ohms.

25. What is the total voltage of two 6-volt batteries connected in parallel?
48 volts
6 volts.
Direct current.
15 minutes.

26. The combined resistance of two resistors in parallel is...
Better speed control on motors.
Less than the resistance of either resistor.
Ventilation.
Reverse.

27. How long should treatment for shock be continued?
Current that flows in only one direction.
6 volts.
Ventilation.
Until the victim receives medical attention.

28. The unit of measurement of power is...
Watts.
A wire wound resistor.
500 volts.
4.0 ohms.

29. What is Ohm's Law?
Distance.
E=IR.
It must prevent ignition of surrounding methane atmosphere.
Burns will appear only at the point where contact is made to the energized circuit.

30. Resistance is measured with a...
Series-wound.
Current.
400 ampere-hours.
Ohmmeter.

31. What is the total resistance of four 25-ohm resistors connected in series?
100 ohms
Higher current with voltage remaining the same.
4.0 ohms.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

32. What is the first step in treating a chemical burn of the eye?
In series.
Decrease.
Watts.
Flush the burn the clean water.

33. What voltage is required to force 5 amps through a 15-ohm resistor?
It must prevent internal explosions.
In series.
75 volts.
Flush thoroughly with water.

34. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
Flush thoroughly with water.
500 volts.
Hydrogen.

35. Trailing cable on DC-powered mobile haulage equipment must be at least...
Resistance.
Soft iron.
No.4 AWG.
Distance.

36. What should be used in treating an eye injury caused by battery acid?
Clean water.
48 volts
Current.
75 volts.

37. Unlike poles of a magnet will...
A. Total resistance is less than the smallest resistor.
Watts.
746 watts.
Attract each other.

38. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
Clean water.
4.0 ohms.
Ventilation.

39. Which of the following motors are considered to be constant or nearly constant speed?
Repel each other.
Compound-wound and shunt-wound.
60 ohms.
96 volts.

40. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
4.8 ohms
4.0 ohms.
A wire wound resistor.
746 watts.

41. The best insulator against the lines of magnetic force is...
6 volts.
Series-wound.
In series.
Distance.

42. What is the total resistance of four 15-ohm resistors connected in series?
746 watts.
60 ohms.
Clean water.
36 volts.

43. Voltage is measured with a...
500 volts.
Wattmeter.
Voltmeter.
Attract each other.

44. What is the opposition to flow of electric current?
Current that flows in only one direction.
96 volts.
200 volts
Resistance.

45. What is the unit of electromotive force or electric pressure?
Voltage.
The opposition to flow of electrons in a circuit.
Current.
In parallel.

46. 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...
Flush thoroughly with water.
Treat for physical shock.
Power.
Distance.

47. The armature of a direct current motor - when running - generates...
A counter-EMF.
Current that flows in only one direction.
In series.
The opposition to flow of electrons in a circuit.

48. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
Better speed control on motors.
The opposition to flow of electrons in a circuit.
Ventilation.

49. The longer the conductor - the greater the...
Watts.
Less than the resistance of either resistor.
Higher current with voltage remaining the same.
Resistance.

50. What is the flow of electrons in a conductor?
Clean water.
Current.
Watts.
400 ampere-hours.