Test your basic knowledge |

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?
A wire wound resistor.
400 ampere-hours.
Current that flows in only one direction.
Until the victim receives medical attention.

2. Which of the following stays the same in all parts of a series circuit?
Soft iron.
Current
400 ampere-hours.
Treat for physical shock.

3. A triac is?
A bi-directional device that can pass current in either direction.
Watts.
Less than the resistance of either resistor.
Until the victim receives medical attention.

4. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
In parallel.
The opposition to flow of electrons in a circuit.
Power.
No.4 AWG.

5. Voltage in a parallel circuit...
No.4 AWG.
It must prevent ignition of surrounding methane atmosphere.
Voltage.
Stays the same.

6. The most common reason that solid state devices fail is...
Soft iron.
It must prevent internal explosions.
Heat
A counter-EMF.

7. The unit of measurement of current is...
Attract each other.
Decrease.
36 volts.
Amperes.

8. When should water be added to a battery?
Repel each other.
It must prevent ignition of surrounding methane atmosphere.
After charging
Watts.

9. The first step in treating a chemical burn - such as one caused by battery acid - is to...
8 ohms.
Flush thoroughly with water.
400 ampere-hours.
Current

10. Like poles of a magnet will...
After charging
Less than the resistance of either resistor.
Repel each other.
Compound-wound and shunt-wound.

11. Resistance is measured with a...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Burns will appear only at the point where contact is made to the energized circuit.
Ohmmeter.
Direct current.

12. What is the total voltage of two 6-volt batteries connected in parallel?
6 volts.
200 volts
Watts.
Burns will appear only at the point where contact is made to the energized circuit.

13. What is the total voltage of four 12-volt batteries connected in series?
Ohms.
Repel each other.
48 volts
Watts.

14. How must two 12-volt batteries be connected in order to increase the current capacity?
In parallel.
4.8 ohms
15 minutes.
48 volts

15. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Less than the resistance of either resistor.
4.8 ohms
Ohmmeter.
Wattmeter.

16. The explosive gas that is generated when a battery is charging is...
746 watts.
96 volts.
Hydrogen.
The movement of electrons in a circuit.

17. What is the flow of electrons in a conductor?
Current.
8 ohms.
Flush the burn the clean water.
Ohmmeter.

18. Not true about electrical shocks?
In series.
746 watts.
Burns will appear only at the point where contact is made to the energized circuit.
1.260 to 1.280.

19. The combined resistance of two resistors in parallel is...
Burns will appear only at the point where contact is made to the energized circuit.
In series.
Stays the same.
Less than the resistance of either resistor.

20. What should be used in treating an eye injury caused by battery acid?
Better speed control on motors.
Wattmeter.
746 watts.
Clean water.

21. Not a requirement of an explosion-proof enclosure?
It must prevent internal explosions.
A counter-EMF.
No.4 AWG.
4.0 ohms.

22. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
Reverse.
Higher current with voltage remaining the same.
Resistance.

23. Power is measured with a...
Soft iron.
8 ohms.
Wattmeter.
Direct current.

24. Unlike poles of a magnet will...
Better speed control on motors.
Higher current with voltage remaining the same.
Attract each other.
500 volts.

25. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
In parallel.
The opposition to flow of electrons in a circuit.
Until the victim receives medical attention.

26. The advantage of DC over AC is that DC offers...
In parallel.
Voltmeter.
Ventilation.
Better speed control on motors.

27. What is the rate that work is done or heat is dissipated?
Direct current.
The movement of electrons in a circuit.
Power.
Better speed control on motors.

28. Define current...
Clean water.
The movement of electrons in a circuit.
After charging
200 volts

29. Which current flows in only one direction?
60 ohms.
Attract each other.
36 volts.
Direct current.

30. What voltage is required to force 5 amps through a 15-ohm resistor?
The movement of electrons in a circuit.
Distance.
Resistance.
75 volts.

31. The instrument used to check the electrolyte of a battery is a...
Decrease.
Hydrometer.
1.260 to 1.280.
Voltage.

32. Batteries connected in parallel provide...
Ventilation.
Ohmmeter.
Higher current with voltage remaining the same.
200 volts

33. Trailing cable on DC-powered mobile haulage equipment must be at least...
No.4 AWG.
Ammeter.
Ventilation.
36 volts.

34. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Clean water.
Hydrogen.
A. Total resistance is less than the smallest resistor.
Ohmmeter.

35. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Current that flows in one direction only.
Heat
400 ampere-hours.
6 volts.

36. Define direct current...
6 volts.
Until the victim receives medical attention.
36 volts.
Current that flows in only one direction.

37. What is Ohm's Law?
15 minutes.
E=IR.
8 ohms.
Distance.

38. What must be provided at underground battery charging stations?
Voltage.
Burns will appear only at the point where contact is made to the energized circuit.
Ventilation.
15 minutes.

39. The unit of measurement of power is...
Flush the burn the clean water.
Amperes.
Ohmmeter.
Watts.

40. What voltage would be required to force 10 amps through a 20-ohm resistor?
Voltage.
75 volts.
200 volts
Less than the resistance of either resistor.

41. The unit of measurement of resistance is?
500 volts.
Ventilation.
Wattmeter.
Ohms.

42. Storage battery charging stations must be provided with what kind of current protection?
Watts.
In series.
Reverse.
96 volts.

43. Define direct current...
The opposition to flow of electrons in a circuit.
Wattmeter.
Current that flows in one direction only.
In series.

44. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
In parallel.
Resistance.
Burns will appear only at the point where contact is made to the energized circuit.

45. In a parallel circuit...
Less than the resistance of either resistor.
It must prevent internal explosions.
1.260 to 1.280.
A. Total resistance is less than the smallest resistor.

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...
4.8 ohms
No.4 AWG.
Treat for physical shock.
In series.

47. How many watts are in one horsepower?
Ohmmeter.
746 watts.
Resistance.
Power.

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

49. The best insulator against the lines of magnetic force is...
Wattmeter.
Distance.
8 ohms.
In series.

50. The longer the conductor - the greater the...
1.260 to 1.280.
Resistance.
In series.
Ohmmeter.