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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. What must be provided at underground battery charging stations?
Ventilation.
Reverse.
Direct current.
Hydrogen.

2. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
A bi-directional device that can pass current in either direction.
The opposition to flow of electrons in a circuit.
In series.
A counter-EMF.

3. Which current flows in only one direction?
Direct current.
Heat
Higher current with voltage remaining the same.
Ohms.

4. How long should treatment for shock be continued?
In series.
Compound-wound and shunt-wound.
Until the victim receives medical attention.
A counter-EMF.

5. Voltage in a parallel circuit...
It must prevent ignition of surrounding methane atmosphere.
Stays the same.
Watts.
Hydrogen.

6. What voltage would be required to force 10 amps through a 50-ohm resistor?
A bi-directional device that can pass current in either direction.
No.4 AWG.
E=IR.
500 volts.

7. Not an electro-magnet?
A wire wound resistor.
Series-wound.
Less than the resistance of either resistor.
The movement of electrons in a circuit.

8. What is Ohm's Law?
E=IR.
Treat for physical shock.
Soft iron.
4.0 ohms.

9. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
Better speed control on motors.
746 watts.
Current that flows in only one direction.
4.0 ohms.

10. Chemical burns caused by battery acid should be washed with clean water for at least...
8 ohms.
15 minutes.
The movement of electrons in a circuit.
Stays the same.

11. The core of an electro-magnet should be made of...
E=IR.
15 minutes.
500 volts.
Soft iron.

12. What is the unit of electromotive force or electric pressure?
Ohmmeter.
Hydrometer.
Higher current with voltage remaining the same.
Voltage.

13. What voltage is required to force 5 amps through a 15-ohm resistor?
15 minutes.
Decrease.
In series.
75 volts.

14. Unlike poles of a magnet will...
Current that flows in only one direction.
A bi-directional device that can pass current in either direction.
Resistance.
Attract each other.

15. Storage battery charging stations must be provided with what kind of current protection?
Resistance.
Reverse.
It must prevent ignition of surrounding methane atmosphere.
Current that flows in one direction only.

16. What is the total resistance of four 25-ohm resistors connected in series?
100 ohms
Flush thoroughly with water.
After charging
48 volts

17. The best insulator against the lines of magnetic force is...
4.8 ohms
Clean water.
Distance.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

18. Define direct current...
37.3 kilowatts
Current that flows in one direction only.
200 volts
Hydrometer.

19. The unit of measurement of current is...
No.4 AWG.
37.3 kilowatts
Amperes.
Soft iron.

20. Which of the following motors are considered to be constant or nearly constant speed?
Ohmmeter.
Stays the same.
4.0 ohms.
Compound-wound and shunt-wound.

21. Batteries connected in parallel provide...
36 volts.
Clean water.
Higher current with voltage remaining the same.
Power.

22. The combined resistance of two resistors in parallel is...
Wattmeter.
Soft iron.
Less than the resistance of either resistor.
Until the victim receives medical attention.

23. When should water be added to a battery?
After charging
A. Total resistance is less than the smallest resistor.
Resistance.
Power.

24. How many watts are in one horsepower?
Voltmeter.
Repel each other.
746 watts.
75 volts.

25. How must two 12-volt batteries be connected in order to increase the current capacity?
60 ohms.
Compound-wound and shunt-wound.
In parallel.
75 volts.

26. Like poles of a magnet will...
746 watts.
Repel each other.
Higher current with voltage remaining the same.
A wire wound resistor.

27. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
4.8 ohms
4.0 ohms.
Power.
Stays the same.

28. What is the first step in treating a chemical burn of the eye?
Ammeter.
Flush the burn the clean water.
Until the victim receives medical attention.
Resistance.

29. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
100 ohms
Compound-wound and shunt-wound.
8 ohms.
Treat for physical shock.

30. What is the rate that work is done or heat is dissipated?
Power.
60 ohms.
Hydrogen.
Distance.

31. The advantage of DC over AC is that DC offers...
Better speed control on motors.
Flush thoroughly with water.
Heat
Direct current.

32. The armature of a direct current motor - when running - generates...
Clean water.
In series.
Compound-wound and shunt-wound.
A counter-EMF.

33. Resistance is measured with a...
Ohmmeter.
Direct current.
The opposition to flow of electrons in a circuit.
400 ampere-hours.

34. Power is measured with a...
36 volts.
Hydrometer.
Wattmeter.
100 ohms

35. Define resistance...
Ventilation.
The opposition to flow of electrons in a circuit.
500 volts.
Current

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

37. The specific gravity of the electrolyte of a fully charged battery should be...
60 ohms.
Less than the resistance of either resistor.
48 ohms.
1.260 to 1.280.

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

39. The instrument used to check the electrolyte of a battery is a...
Hydrometer.
15 minutes.
75 volts.
Higher current with voltage remaining the same.

40. The most common reason that solid state devices fail is...
Heat
Voltmeter.
Resistance.
Better speed control on motors.

41. The unit of measurement of resistance is?
8 ohms.
Hydrogen.
Ohms.
Repel each other.

42. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Until the victim receives medical attention.
E=IR.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
In series.

43. The minimum allowable size of trailing cable on DC-powered mobile haulage equipment is...
Treat for physical shock.
No.4 AWG.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Current.

44. The unit of measurement of power is...
200 volts
Watts.
In parallel.
Voltage.

45. What voltage would be required to force 10 amps through a 20-ohm resistor?
60 ohms.
Voltmeter.
Hydrometer.
200 volts

46. In a parallel circuit...
500 volts.
8 ohms.
The movement of electrons in a circuit.
A. Total resistance is less than the smallest resistor.

47. Current is measured with a (an)...
Ammeter.
No.4 AWG.
Wattmeter.
4.0 ohms.

48. A triac is?
A bi-directional device that can pass current in either direction.
No.4 AWG.
Decrease.
Higher current with voltage remaining the same.

49. What is the total voltage of two 6-volt batteries connected in parallel?
4.0 ohms.
15 minutes.
In series.
6 volts.

50. Current in a series circuit...
Heat
The movement of electrons in a circuit.
Treat for physical shock.
Stays the same.