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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?
400 ampere-hours.
48 volts
Decrease.
Ventilation.

2. Not an electro-magnet?
E=IR.
Wattmeter.
A wire wound resistor.
Watts.

3. The first step in treating a chemical burn - such as one caused by battery acid - is to...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
15 minutes.
Flush thoroughly with water.
A bi-directional device that can pass current in either direction.

4. What is the total voltage of two 6-volt batteries connected in parallel?
6 volts.
Stays the same.
Clean water.
500 volts.

5. What is the total resistance of three 16-ohm resistors connected in series?
After charging
Current that flows in only one direction.
48 ohms.
A wire wound resistor.

6. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Burns will appear only at the point where contact is made to the energized circuit.
It must prevent ignition of surrounding methane atmosphere.
In series.
A wire wound resistor.

7. Which of the following motors CANNOT be run without a load?
Current.
Series-wound.
No.4 AWG.
Hydrogen.

8. What is the total resistance of four 25-ohm resistors connected in series?
6 volts.
100 ohms
Current
36 volts.

9. Current in a series circuit...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
E=IR.
Stays the same.
Better speed control on motors.

10. Resistance is measured with a...
Ohmmeter.
Current that flows in only one direction.
37.3 kilowatts
Series-wound.

11. What is the first step in treating a chemical burn of the eye?
Flush the burn the clean water.
6 volts.
Hydrometer.
4.0 ohms.

12. Define direct current...
Hydrogen.
100 ohms
Current that flows in one direction only.
Clean water.

13. In a parallel circuit...
It must prevent ignition of surrounding methane atmosphere.
A. Total resistance is less than the smallest resistor.
15 minutes.
60 ohms.

14. Define current...
36 volts.
The movement of electrons in a circuit.
Reverse.
Resistance.

15. What is the total voltage of four 12-volt batteries connected in series?
400 ampere-hours.
No.4 AWG.
Treat for physical shock.
48 volts

16. Which of the following is a requirement of an explosion-proof enclosure?
It must prevent ignition of surrounding methane atmosphere.
Voltage.
E=IR.
Ventilation.

17. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
6 volts.
Hydrometer.
It must prevent internal explosions.
Hydrogen.

18. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
500 volts.
A counter-EMF.
4.0 ohms.
Amperes.

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

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20. The core of an electro-magnet should be made of...
A bi-directional device that can pass current in either direction.
Ammeter.
A counter-EMF.
Soft iron.

21. What is the total voltage of four 9-volt batteries connected in a series?
Treat for physical shock.
36 volts.
E=IR.
Ohms.

22. What voltage would be required to force 10 amps through a 50-ohm resistor?
Treat for physical shock.
Clean water.
500 volts.
Better speed control on motors.

23. What is the rate that work is done or heat is dissipated?
Voltmeter.
Power.
Current
A. Total resistance is less than the smallest resistor.

24. The most common reason that solid state devices fail is...
Current that flows in only one direction.
Voltmeter.
It must prevent internal explosions.
Heat

25. Like poles of a magnet will...
Direct current.
Amperes.
Repel each other.
Voltmeter.

26. Power is measured with a...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Wattmeter.
Attract each other.
100 ohms

27. What should be used in treating an eye injury caused by battery acid?
Current
Clean water.
500 volts.
Hydrometer.

28. Which of the following motors are considered to be constant or nearly constant speed?
Power.
Better speed control on motors.
Series-wound.
Compound-wound and shunt-wound.

29. Resistors are rated in ohms and...
Watts.
Stays the same.
48 ohms.
Power.

30. Voltage is measured with a...
Voltmeter.
4.8 ohms
Flush thoroughly with water.
A bi-directional device that can pass current in either direction.

31. How must two 12-volt batteries be connected in order to increase the current capacity?
Series-wound.
In parallel.
Flush thoroughly with water.
In series.

32. Voltage in a parallel circuit...
75 volts.
Power.
Ohmmeter.
Stays the same.

33. The armature of a direct current motor - when running - generates...
It must prevent internal explosions.
Stays the same.
Current that flows in one direction only.
A counter-EMF.

34. How many kilowatts are used to develop 50 horsepower?
37.3 kilowatts
60 ohms.
Higher current with voltage remaining the same.
Amperes.

35. The unit of measurement of current is...
Amperes.
No.4 AWG.
Current that flows in only one direction.
48 volts

36. Not true about electrical shocks?
Heat
No.4 AWG.
Burns will appear only at the point where contact is made to the energized circuit.
500 volts.

37. What is the unit of electromotive force or electric pressure?
Voltage.
A wire wound resistor.
Power.
Current that flows in one direction only.

38. The best insulator against the lines of magnetic force is...
Distance.
37.3 kilowatts
Until the victim receives medical attention.
96 volts.

39. When should water be added to a battery?
After charging
Flush the burn the clean water.
Burns will appear only at the point where contact is made to the energized circuit.
Clean water.

40. The longer the conductor - the greater the...
Less than the resistance of either resistor.
Resistance.
Better speed control on motors.
Series-wound.

41. Unlike poles of a magnet will...
Repel each other.
Direct current.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Attract each other.

42. What is the opposition to flow of electric current?
60 ohms.
Flush the burn the clean water.
Attract each other.
Resistance.

43. Current is measured with a (an)...
Ammeter.
400 ampere-hours.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Direct current.

44. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Until the victim receives medical attention.
4.8 ohms
It must prevent internal explosions.
In parallel.

45. How long should treatment for shock be continued?
Burns will appear only at the point where contact is made to the energized circuit.
Watts.
75 volts.
Until the victim receives medical attention.

46. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
No.4 AWG.
8 ohms.
100 ohms
Watts.

47. Batteries connected in parallel provide...
Direct current.
Reverse.
Higher current with voltage remaining the same.
Distance.

48. A triac is?
200 volts
Hydrogen.
Current that flows in one direction only.
A bi-directional device that can pass current in either direction.

49. The instrument used to check the electrolyte of a battery is a...
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Voltage.
Burns will appear only at the point where contact is made to the energized circuit.
Hydrometer.

50. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Hydrogen.
400 ampere-hours.
Hydrogen.
Better speed control on motors.