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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 is the flow of electrons in a conductor?
Watts.
Current.
In series.
Voltage.

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

3. Which current flows in only one direction?
Direct current.
Current.
Burns will appear only at the point where contact is made to the energized circuit.
No.4 AWG.

4. What should be used in treating an eye injury caused by battery acid?
Reverse.
Clean water.
Stays the same.
Ammeter.

5. When should water be added to a battery?
After charging
Soft iron.
Resistance.
75 volts.

6. What voltage would be required to force 10 amps through a 50-ohm resistor?
Current
Stays the same.
500 volts.
Series-wound.

7. The unit of measurement of resistance is?
Current
Ohms.
Direct current.
Amperes.

8. If the cross-sectional area of a conductor is increased - its resistance will...
Hydrometer.
Stays the same.
Decrease.
After charging

9. Chemical burns caused by battery acid should be washed with clean water for at least...
A. Total resistance is less than the smallest resistor.
Resistance.
15 minutes.
In parallel.

10. What is the total resistance of three 16-ohm resistors connected in series?
Resistance.
48 ohms.
Power.
The movement of electrons in a circuit.

11. Batteries connected in parallel provide...
After charging
Higher current with voltage remaining the same.
4.0 ohms.
Distance.

12. The longer the conductor - the greater the...
Attract each other.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
48 ohms.
Resistance.

13. What is Ohm's Law?
Series-wound.
Flush thoroughly with water.
Direct current.
E=IR.

14. The core of an electro-magnet should be made of...
Ohmmeter.
Compound-wound and shunt-wound.
Soft iron.
Less than the resistance of either resistor.

15. The unit of measurement of current is...
The movement of electrons in a circuit.
Amperes.
Hydrogen.
Burns will appear only at the point where contact is made to the energized circuit.

16. In a parallel circuit...
Treat for physical shock.
Ohmmeter.
A. Total resistance is less than the smallest resistor.
Resistance.

17. A triac is?
Better speed control on motors.
No.4 AWG.
48 ohms.
A bi-directional device that can pass current in either direction.

18. Define current...
Power.
100 ohms
The movement of electrons in a circuit.
In series.

19. What is the unit of electromotive force or electric pressure?
Ohms.
Voltage.
Distance.
4.0 ohms.

20. Voltage is measured with a...
400 ampere-hours.
500 volts.
Voltmeter.
No.4 AWG.

21. What is the rate that work is done or heat is dissipated?
Power.
Hydrometer.
200 volts
The movement of electrons in a circuit.

22. What is the equivalent resistance of two 16-ohm resistors connected in parallel?
There is a hazard of blowing the contents back into your face - 'explosive reaction'.
Current that flows in one direction only.
Series-wound.
8 ohms.

23. Unlike poles of a magnet will...
Attract each other.
200 volts
Resistance.
Clean water.

24. What must be provided at underground battery charging stations?
Reverse.
Distance.
Stays the same.
Ventilation.

25. The unit of measurement of power is...
Watts.
Soft iron.
A. Total resistance is less than the smallest resistor.
200 volts

26. Storage battery charging stations must be provided with what kind of current protection?
A. Total resistance is less than the smallest resistor.
Current
4.8 ohms
Reverse.

27. Which of the following motors are considered to be constant or nearly constant speed?
Compound-wound and shunt-wound.
A counter-EMF.
It must prevent ignition of surrounding methane atmosphere.
200 volts

28. Which of the following motors CANNOT be run without a load?
A. Total resistance is less than the smallest resistor.
No.4 AWG.
Watts.
Series-wound.

29. The best insulator against the lines of magnetic force is...
Ammeter.
Distance.
It must prevent ignition of surrounding methane atmosphere.
Heat

30. Power is measured with a...
100 ohms
4.0 ohms.
Current that flows in one direction only.
Wattmeter.

31. The armature of a direct current motor - when running - generates...
1.260 to 1.280.
A counter-EMF.
200 volts
Voltage.

32. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
Less than the resistance of either resistor.
A bi-directional device that can pass current in either direction.
Heat
4.8 ohms

33. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
37.3 kilowatts
96 volts.
4.0 ohms.
Voltmeter.

34. What voltage is required to force 5 amps through a 15-ohm resistor?
Voltmeter.
36 volts.
75 volts.
A. Total resistance is less than the smallest resistor.

35. You have three 9-volt batteries. How should you connect them in order to supply 27 volts?
Resistance.
Amperes.
Clean water.
In series.

36. Voltage in a parallel circuit...
Better speed control on motors.
Stays the same.
500 volts.
Soft iron.

37. How many watts are in one horsepower?
48 ohms.
Hydrogen.
746 watts.
Less than the resistance of either resistor.

38. What is the total voltage of four 9-volt batteries connected in a series?
Amperes.
36 volts.
After charging
Decrease.

39. Not true about electrical shocks?
Until the victim receives medical attention.
Current that flows in only one direction.
A counter-EMF.
Burns will appear only at the point where contact is made to the energized circuit.

40. The first step in treating a chemical burn - such as one caused by battery acid - is to...
500 volts.
Flush thoroughly with water.
15 minutes.
Amperes.

41. The instrument used to check the electrolyte of a battery is a...
A. Total resistance is less than the smallest resistor.
Hydrometer.
8 ohms.
400 ampere-hours.

42. Not a requirement of an explosion-proof enclosure?
It must prevent internal explosions.
Compound-wound and shunt-wound.
Current.
Current that flows in only one direction.

43. What voltage would be required to force 10 amps through a 20-ohm resistor?
After charging
400 ampere-hours.
200 volts
Hydrogen.

44. A battery capable of producing 20 amperes steadily for 20 hours at 80 degrees Fahrenheit would have an ampere-hour rating of...
Reverse.
15 minutes.
60 ohms.
400 ampere-hours.

45. Resistance is measured with a...
Higher current with voltage remaining the same.
Compound-wound and shunt-wound.
Current.
Ohmmeter.

46. Which of the following stays the same in all parts of a series circuit?
37.3 kilowatts
It must prevent internal explosions.
100 ohms
Current

47. 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...
Voltage.
Watts.
Treat for physical shock.
There is a hazard of blowing the contents back into your face - 'explosive reaction'.

48. How must two 12-volt batteries be connected in order to increase the current capacity?
Watts.
In parallel.
Ohms.
Reverse.

49. What is the total resistance of four 15-ohm resistors connected in series?
60 ohms.
400 ampere-hours.
8 ohms.
E=IR.

50. Resistors are rated in ohms and...
8 ohms.
6 volts.
Watts.
15 minutes.