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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 combined resistance of two resistors in parallel is...
48 volts
Less than the resistance of either resistor.
Flush thoroughly with water.
Burns will appear only at the point where contact is made to the energized circuit.

2. What is the total resistance of four 15-ohm resistors connected in series?
A. Total resistance is less than the smallest resistor.
746 watts.
15 minutes.
60 ohms.

3. How must two 12-volt batteries be connected in order to increase the current capacity?
A. Total resistance is less than the smallest resistor.
Resistance.
In parallel.
A wire wound resistor.

4. Resistors are rated in ohms and...
Series-wound.
In series.
Less than the resistance of either resistor.
Watts.

5. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
Stays the same.
The opposition to flow of electrons in a circuit.
Ohms.

6. What is the total resistance of three 16-ohm resistors connected in series?
48 ohms.
In series.
Hydrogen.
Burns will appear only at the point where contact is made to the energized circuit.

7. Which of the following motors CANNOT be run without a load?
Less than the resistance of either resistor.
Series-wound.
Decrease.
Watts.

8. Not true about electrical shocks?
60 ohms.
Burns will appear only at the point where contact is made to the energized circuit.
Resistance.
Flush the burn the clean water.

9. The first step in treating a chemical burn - such as one caused by battery acid - is to...
Flush thoroughly with water.
Hydrometer.
Until the victim receives medical attention.
Compound-wound and shunt-wound.

10. What should be used in treating an eye injury caused by battery acid?
Attract each other.
Clean water.
Direct current.
Ohms.

11. Which of the following is a requirement of an explosion-proof enclosure?
Watts.
Better speed control on motors.
It must prevent ignition of surrounding methane atmosphere.
Reverse.

12. The explosive gas that is generated when a battery is charging is...
Hydrogen.
Current that flows in only one direction.
1.260 to 1.280.
Stays the same.

13. What is the total voltage of four 12-volt batteries connected in series?
400 ampere-hours.
Current that flows in only one direction.
48 volts
Ammeter.

14. Current is measured with a (an)...
60 ohms.
Resistance.
Ammeter.
Clean water.

15. What voltage is required to force 5 amps through a 15-ohm resistor?
75 volts.
1.260 to 1.280.
Resistance.
15 minutes.

16. Not a requirement of an explosion-proof enclosure?
A bi-directional device that can pass current in either direction.
It must prevent internal explosions.
No.4 AWG.
75 volts.

17. The specific gravity of the electrolyte of a fully charged battery should be...
A wire wound resistor.
1.260 to 1.280.
Current that flows in only one direction.
Distance.

18. What must be provided at underground battery charging stations?
Higher current with voltage remaining the same.
Ventilation.
Clean water.
Ohms.

19. The advantage of DC over AC is that DC offers...
Better speed control on motors.
48 ohms.
Repel each other.
8 ohms.

20. Not an electro-magnet?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Direct current.
48 ohms.
A wire wound resistor.

21. The unit of measurement of power is...
It must prevent internal explosions.
A wire wound resistor.
Watts.
Wattmeter.

22. The longer the conductor - the greater the...
Current.
Ammeter.
36 volts.
Resistance.

23. What voltage would be required to force 10 amps through a 20-ohm resistor?
Decrease.
200 volts
96 volts.
Watts.

24. Storage battery charging stations must be provided with what kind of current protection?
Amperes.
Decrease.
37.3 kilowatts
Reverse.

25. A triac is?
Better speed control on motors.
In parallel.
Hydrogen.
A bi-directional device that can pass current in either direction.

26. What is the total voltage of two 6-volt batteries connected in parallel?
Direct current.
Treat for physical shock.
6 volts.
Burns will appear only at the point where contact is made to the energized circuit.

27. Unlike poles of a magnet will...
Hydrogen.
Attract each other.
Series-wound.
500 volts.

28. How many watts are in one horsepower?
Current that flows in only one direction.
746 watts.
Burns will appear only at the point where contact is made to the energized circuit.
A. Total resistance is less than the smallest resistor.

29. Which of the following stays the same in all parts of a series circuit?
1.260 to 1.280.
96 volts.
Ventilation.
Current

30. How long should treatment for shock be continued?
Watts.
A bi-directional device that can pass current in either direction.
E=IR.
Until the victim receives medical attention.

31. If the cross-sectional area of a conductor is increased - its resistance will...
75 volts.
Decrease.
The opposition to flow of electrons in a circuit.
Clean water.

32. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Higher current with voltage remaining the same.
A counter-EMF.
The movement of electrons in a circuit.
8 ohms.

33. Define current...
Decrease.
Better speed control on motors.
No.4 AWG.
The movement of electrons in a circuit.

34. Current in a series circuit...
Heat
Ohms.
Stays the same.
Hydrometer.

35. When should water be added to a battery?
Watts.
After charging
Compound-wound and shunt-wound.
100 ohms

36. Like poles of a magnet will...
4.8 ohms
Ventilation.
48 volts
Repel each other.

37. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Treat for physical shock.
Resistance.
In series.
The opposition to flow of electrons in a circuit.

38. How many kilowatts are used to develop 50 horsepower?
It must prevent ignition of surrounding methane atmosphere.
37.3 kilowatts
Current
E=IR.

39. The instrument used to check the electrolyte of a battery is a...
6 volts.
Until the victim receives medical attention.
Clean water.
Hydrometer.

40. Define direct current...
A bi-directional device that can pass current in either direction.
Distance.
Flush thoroughly with water.
Current that flows in only one direction.

41. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Current that flows in only one direction.
200 volts
In series.
Distance.

42. Define resistance...
Clean water.
Stays the same.
The opposition to flow of electrons in a circuit.
Series-wound.

43. Which current flows in only one direction?
Treat for physical shock.
746 watts.
15 minutes.
Direct current.

44. What is the first step in treating a chemical burn of the eye?
Flush the burn the clean water.
60 ohms.
In series.
4.0 ohms.

45. The unit of measurement of resistance is?
Ohms.
Ohmmeter.
A wire wound resistor.
96 volts.

46. The best insulator against the lines of magnetic force is...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
After charging
Distance.
A wire wound resistor.

47. 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...
Until the victim receives medical attention.
Treat for physical shock.
15 minutes.
No.4 AWG.

48. What is Ohm's Law?
48 volts
Hydrogen.
E=IR.
Stays the same.

49. What voltage would be required to force 10 amps through a 50-ohm resistor?
96 volts.
500 volts.
Hydrogen.
6 volts.

50. Voltage in a parallel circuit...
Current that flows in one direction only.
Ammeter.
Stays the same.
Treat for physical shock.