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. What is the total voltage of two 6-volt batteries connected in parallel?
Hydrogen.
After charging
Higher current with voltage remaining the same.
6 volts.

2. Define current...
The movement of electrons in a circuit.
36 volts.
746 watts.
No.4 AWG.

3. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
Current that flows in one direction only.
The movement of electrons in a circuit.
Ventilation.

4. What is the opposition to flow of electric current?
Resistance.
A. Total resistance is less than the smallest resistor.
It must prevent ignition of surrounding methane atmosphere.
Watts.

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

6. What voltage would be required to force 10 amps through a 50-ohm resistor?
500 volts.
Compound-wound and shunt-wound.
Ventilation.
Amperes.

7. The longer the conductor - the greater the...
Treat for physical shock.
Current
Resistance.
Hydrogen.

8. Like poles of a magnet will...
Repel each other.
8 ohms.
Heat
Voltmeter.

9. How must two 12-volt batteries be connected in order to increase the current capacity?
100 ohms
Ohmmeter.
Less than the resistance of either resistor.
In parallel.

10. What should be used in treating an eye injury caused by battery acid?
It must prevent internal explosions.
In series.
Clean water.
In parallel.

11. Trailing cable on DC-powered mobile haulage equipment must be at least...
It must prevent internal explosions.
Power.
No.4 AWG.
400 ampere-hours.

12. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
A. Total resistance is less than the smallest resistor.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
400 ampere-hours.

13. What is the total voltage of four 9-volt batteries connected in a series?
Current.
Current that flows in only one direction.
Until the victim receives medical attention.
36 volts.

14. Batteries connected in parallel provide...
Attract each other.
Higher current with voltage remaining the same.
37.3 kilowatts
Repel each other.

15. The explosive gas that is generated when a battery is charging is...
A. Total resistance is less than the smallest resistor.
6 volts.
Current
Hydrogen.

16. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
The movement of electrons in a circuit.
100 ohms
4.8 ohms
48 ohms.

17. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
No.4 AWG.
It must prevent ignition of surrounding methane atmosphere.
500 volts.
8 ohms.

18. The instrument used to check the electrolyte of a battery is a...
A bi-directional device that can pass current in either direction.
Soft iron.
In parallel.
Hydrometer.

19. How long should treatment for shock be continued?
Current.
Treat for physical shock.
Hydrogen.
Until the victim receives medical attention.

20. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Current that flows in one direction only.
In series.
A. Total resistance is less than the smallest resistor.
746 watts.

21. The unit of measurement of resistance is?
E=IR.
No.4 AWG.
It must prevent ignition of surrounding methane atmosphere.
Ohms.

22. Which current flows in only one direction?
96 volts.
Distance.
Direct current.
8 ohms.

23. What is the total voltage of eight 12-volt batteries connected in series?
Soft iron.
It must prevent internal explosions.
96 volts.
Watts.

24. How many watts are in one horsepower?
4.0 ohms.
746 watts.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Distance.

25. Resistance is measured with a...
Ohmmeter.
8 ohms.
Current.
In series.

26. What is the rate that work is done or heat is dissipated?
Direct current.
6 volts.
Series-wound.
Power.

27. The core of an electro-magnet should be made of...
Watts.
Higher current with voltage remaining the same.
Soft iron.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

28. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
It must prevent ignition of surrounding methane atmosphere.
500 volts.
400 ampere-hours.
100 ohms

29. What is the total voltage of four 12-volt batteries connected in series?
After charging
Burns will appear only at the point where contact is made to the energized circuit.
48 volts
E=IR.

30. Define resistance...
Voltage.
Treat for physical shock.
The opposition to flow of electrons in a circuit.
4.8 ohms

31. Which of the following motors CANNOT be run without a load?
15 minutes.
It must prevent internal explosions.
Series-wound.
Soft iron.

32. The combined resistance of two resistors in parallel is...
75 volts.
4.0 ohms.
Less than the resistance of either resistor.
Hydrogen.

33. Unlike poles of a magnet will...
96 volts.
746 watts.
Voltmeter.
Attract each other.

34. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Hydrogen.
In series.
200 volts
Voltmeter.

35. Define direct current...
Treat for physical shock.
Clean water.
Compound-wound and shunt-wound.
Current that flows in only one direction.

36. The advantage of DC over AC is that DC offers...
Current that flows in only one direction.
15 minutes.
200 volts
Better speed control on motors.

37. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
Ventilation.
8 ohms.
A. Total resistance is less than the smallest resistor.
It must prevent ignition of surrounding methane atmosphere.

38. What is the unit of electromotive force or electric pressure?
Voltage.
Resistance.
Direct current.
Power.

39. The specific gravity of the electrolyte of a fully charged battery should be...
37.3 kilowatts
Soft iron.
48 volts
1.260 to 1.280.

40. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
746 watts.
Reverse.
200 volts

41. Voltage is measured with a...
Amperes.
E=IR.
Attract each other.
Voltmeter.

42. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
It must prevent internal explosions.
200 volts
60 ohms.

43. What is the total resistance of three 16-ohm resistors connected in series?
In series.
4.0 ohms.
48 ohms.
Ammeter.

44. The unit of measurement of power is...
Resistance.
48 ohms.
Watts.
Ohms.

45. What is the total resistance of four 15-ohm resistors connected in series?
60 ohms.
15 minutes.
Repel each other.
Resistance.

46. The most common reason that solid state devices fail is...
After charging
It must prevent ignition of surrounding methane atmosphere.
Heat
Until the victim receives medical attention.

47. Not a requirement of an explosion-proof enclosure?
15 minutes.
Hydrogen.
No.4 AWG.
It must prevent internal explosions.

48. What voltage would be required to force 10 amps through a 20-ohm resistor?
A. Total resistance is less than the smallest resistor.
200 volts
48 volts
Higher current with voltage remaining the same.

49. Resistors are rated in ohms and...
Current.
746 watts.
It must prevent ignition of surrounding methane atmosphere.
Watts.

50. Current in a series circuit...
Flush the burn the clean water.
The movement of electrons in a circuit.
Reverse.
Stays the same.