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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. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
In series.
Power.
Soft iron.
Decrease.

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

3. Define direct current...
Current that flows in only one direction.
60 ohms.
75 volts.
The opposition to flow of electrons in a circuit.

4. Current is measured with a (an)...
Ammeter.
746 watts.
Hydrogen.
48 volts

5. The best insulator against the lines of magnetic force is...
Stays the same.
Distance.
After charging
96 volts.

6. Define direct current...
Treat for physical shock.
Current that flows in one direction only.
The movement of electrons in a circuit.
48 volts

7. What is the total voltage of four 12-volt batteries connected in series?
Burns will appear only at the point where contact is made to the energized circuit.
Soft iron.
48 volts
In series.

8. The armature of a direct current motor - when running - generates...
500 volts.
A counter-EMF.
37.3 kilowatts
A wire wound resistor.

9. Define current...
Ohmmeter.
Voltmeter.
The movement of electrons in a circuit.
No.4 AWG.

10. Batteries connected in parallel provide...
Higher current with voltage remaining the same.
Ohmmeter.
500 volts.
Current that flows in one direction only.

11. The most common reason that solid state devices fail is...
E=IR.
Amperes.
Heat
In series.

12. What must be provided at underground battery charging stations?
Distance.
Decrease.
Current.
Ventilation.

13. The unit of measurement of resistance is?
Ohms.
Voltmeter.
400 ampere-hours.
1.260 to 1.280.

14. What is the unit of electromotive force or electric pressure?
Better speed control on motors.
Flush thoroughly with water.
Voltage.
Current that flows in one direction only.

15. Define resistance...
In series.
The opposition to flow of electrons in a circuit.
Less than the resistance of either resistor.
Repel each other.

16. The specific gravity of the electrolyte of a fully charged battery should be...
400 ampere-hours.
Reverse.
The movement of electrons in a circuit.
1.260 to 1.280.

17. Not true about electrical shocks?
Voltmeter.
Better speed control on motors.
Hydrometer.
Burns will appear only at the point where contact is made to the energized circuit.

18. What is the total voltage of two 6-volt batteries connected in parallel?
6 volts.
Resistance.
Hydrogen.
Stays the same.

19. Resistance is measured with a...
Repel each other.
Ohmmeter.
Resistance.
A counter-EMF.

20. What is the rate that work is done or heat is dissipated?
8 ohms.
Current
A wire wound resistor.
Power.

21. Voltage is measured with a...
Repel each other.
Voltmeter.
A counter-EMF.
In series.

22. How many watts are in one horsepower?
In parallel.
746 watts.
Stays the same.
Reverse.

23. The explosive gas that is generated when a battery is charging is...
8 ohms.
Ohms.
Hydrogen.
No.4 AWG.

24. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Flush the burn the clean water.
E=IR.
8 ohms.
400 ampere-hours.

25. If the cross-sectional area of a conductor is increased - its resistance will...
48 ohms.
Decrease.
Current that flows in only one direction.
Power.

26. Unlike poles of a magnet will...
Attract each other.
Heat
500 volts.
Better speed control on motors.

27. What is the total resistance of four 15-ohm resistors connected in series?
Current.
60 ohms.
1.260 to 1.280.
Burns will appear only at the point where contact is made to the energized circuit.

28. The longer the conductor - the greater the...
After charging
Resistance.
Flush the burn the clean water.
In series.

29. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
The movement of electrons in a circuit.
4.0 ohms.
200 volts
In series.

30. What is the total resistance of three 16-ohm resistors connected in series?
Wattmeter.
Clean water.
48 ohms.
Amperes.

31. What should be used in treating an eye injury caused by battery acid?
Clean water.
1.260 to 1.280.
Stays the same.
Ohms.

32. Which of the following is a requirement of an explosion-proof enclosure?
After charging
It must prevent ignition of surrounding methane atmosphere.
Attract each other.
Less than the resistance of either resistor.

33. The core of an electro-magnet should be made of...
Distance.
Soft iron.
Ammeter.
The opposition to flow of electrons in a circuit.

34. Power is measured with a...
48 ohms.
Less than the resistance of either resistor.
Wattmeter.
Current that flows in only one direction.

35. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
4.8 ohms
In series.
No.4 AWG.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

36. The advantage of DC over AC is that DC offers...
Voltage.
Direct current.
75 volts.
Better speed control on motors.

37. How many kilowatts are used to develop 50 horsepower?
In series.
37.3 kilowatts
500 volts.
Voltmeter.

38. Storage battery charging stations must be provided with what kind of current protection?
Reverse.
After charging
75 volts.
It must prevent internal explosions.

39. What is the flow of electrons in a conductor?
Current.
Ohmmeter.
Ventilation.
Voltmeter.

40. Which of the following motors CANNOT be run without a load?
48 ohms.
Current.
Series-wound.
After charging

41. Current in a series circuit...
In parallel.
Current that flows in only one direction.
200 volts
Stays the same.

42. What is Ohm's Law?
In series.
E=IR.
In parallel.
A wire wound resistor.

43. What voltage would be required to force 10 amps through a 20-ohm resistor?
75 volts.
200 volts
Current that flows in only one direction.
No.4 AWG.

44. What voltage would be required to force 10 amps through a 50-ohm resistor?
In series.
A bi-directional device that can pass current in either direction.
500 volts.
Less than the resistance of either resistor.

45. The combined resistance of two resistors in parallel is...
Resistance.
Less than the resistance of either resistor.
96 volts.
Series-wound.

46. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
The opposition to flow of electrons in a circuit.
Resistance.
Series-wound.
No.4 AWG.

47. When should water be added to a battery?
Voltage.
Series-wound.
After charging
48 volts

48. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
In series.
Current that flows in only one direction.
Resistance.
Less than the resistance of either resistor.

49. Trailing cable on DC-powered mobile haulage equipment must be at least...
100 ohms
Current that flows in one direction only.
No.4 AWG.
Direct current.

50. Voltage in a parallel circuit...
Watts.
Higher current with voltage remaining the same.
Stays the same.
Current that flows in one direction only.