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. How many kilowatts are used to develop 50 horsepower?
E=IR.
Direct current.
Watts.
37.3 kilowatts

2. The armature of a direct current motor - when running - generates...
1.260 to 1.280.
A counter-EMF.
In series.
Flush thoroughly with water.

3. What is the first step in treating a chemical burn of the eye?
Resistance.
Reverse.
Flush the burn the clean water.
500 volts.

4. What is the equivalent resistance of an 8-ohm and a 12-ohm resistor connected in parallel?
4.8 ohms
A. Total resistance is less than the smallest resistor.
Hydrogen.
Current

5. Define current...
400 ampere-hours.
The movement of electrons in a circuit.
Ventilation.
Decrease.

6. Not an electro-magnet?
A counter-EMF.
Hydrometer.
Wattmeter.
A wire wound resistor.

7. Which of the following motors are considered to be constant or nearly constant speed?
Hydrogen.
Compound-wound and shunt-wound.
Series-wound.
60 ohms.

8. The unit of measurement of current is...
Series-wound.
Ohmmeter.
Amperes.
Flush thoroughly with water.

9. How long should treatment for shock be continued?
Until the victim receives medical attention.
A bi-directional device that can pass current in either direction.
A. Total resistance is less than the smallest resistor.
Less than the resistance of either resistor.

10. What must be provided at underground battery charging stations?
Attract each other.
Flush thoroughly with water.
Ventilation.
200 volts

11. If the cross-sectional area of a conductor is increased - its resistance will...
Decrease.
Power.
400 ampere-hours.
Voltmeter.

12. Resistors are rated in ohms and...
36 volts.
Watts.
It must prevent ignition of surrounding methane atmosphere.
Until the victim receives medical attention.

13. How must two 12-volt batteries be connected in order to increase the current capacity?
In parallel.
Resistance.
Decrease.
Attract each other.

14. Not a requirement of an explosion-proof enclosure?
Attract each other.
A wire wound resistor.
60 ohms.
It must prevent internal explosions.

15. The combined resistance of two resistors in parallel is...
Less than the resistance of either resistor.
Decrease.
Ohmmeter.
Current.

16. The best insulator against the lines of magnetic force is...
Ammeter.
Decrease.
E=IR.
Distance.

17. A triac is?
8 ohms.
A bi-directional device that can pass current in either direction.
Voltage.
4.8 ohms

18. Not true about electrical shocks?
It must prevent ignition of surrounding methane atmosphere.
Burns will appear only at the point where contact is made to the energized circuit.
A counter-EMF.
Less than the resistance of either resistor.

19. What is the total voltage of two 6-volt batteries connected in parallel?
Wattmeter.
96 volts.
6 volts.
Ventilation.

20. The instrument used to check the electrolyte of a battery is a...
Hydrometer.
In parallel.
The movement of electrons in a circuit.
Burns will appear only at the point where contact is made to the energized circuit.

21. When should water be added to a battery?
After charging
A. Total resistance is less than the smallest resistor.
400 ampere-hours.
The movement of electrons in a circuit.

22. The first step in treating a chemical burn - such as one caused by battery acid - is to...
75 volts.
Repel each other.
Better speed control on motors.
Flush thoroughly with water.

23. 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...
Hydrogen.
Treat for physical shock.
Power.
Current.

24. Chemical burns caused by battery acid should be washed with clean water for at least...
15 minutes.
Flush thoroughly with water.
Direct current.
Hydrogen.

25. Voltage is measured with a...
Voltmeter.
Heat
Ventilation.
Until the victim receives medical attention.

26. Current in a series circuit...
Stays the same.
746 watts.
Better speed control on motors.
36 volts.

27. What is the total resistance of four 25-ohm resistors connected in series?
Voltage.
100 ohms
Treat for physical shock.
In series.

28. How many watts are in one horsepower?
Soft iron.
746 watts.
Watts.
The movement of electrons in a circuit.

29. 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.
Direct current.
Higher current with voltage remaining the same.

30. The most common reason that solid state devices fail is...
Until the victim receives medical attention.
Current that flows in one direction only.
Heat
Hydrogen.

31. Define resistance...
Distance.
Resistance.
The opposition to flow of electrons in a circuit.
Higher current with voltage remaining the same.

32. Batteries connected in parallel provide...
60 ohms.
400 ampere-hours.
Higher current with voltage remaining the same.
Power.

33. What voltage would be required to force 10 amps through a 50-ohm resistor?
Decrease.
500 volts.
Reverse.
Hydrometer.

34. What is the unit of electromotive force or electric pressure?
60 ohms.
Flush thoroughly with water.
Voltage.
A bi-directional device that can pass current in either direction.

35. The core of an electro-magnet should be made of...
Stays the same.
Direct current.
No.4 AWG.
Soft iron.

36. Resistance is measured with a...
Decrease.
Treat for physical shock.
Ohmmeter.
96 volts.

37. What is the opposition to flow of electric current?
Less than the resistance of either resistor.
Ohms.
Current
Resistance.

38. Current is measured with a (an)...
Ammeter.
96 volts.
75 volts.
1.260 to 1.280.

39. What is the total voltage of four 9-volt batteries connected in a series?
Decrease.
Series-wound.
36 volts.
15 minutes.

40. The dangerously explosive gas emitted by charging a lead-acid storage battery is...
Ventilation.
No.4 AWG.
200 volts
Hydrogen.

41. The advantage of DC over AC is that DC offers...
Voltmeter.
Better speed control on motors.
36 volts.
Current.

42. You have three 12-volt batteries. How should you connect them in order to supply 36 volts?
Watts.
Ohms.
In series.
500 volts.

43. In a parallel circuit...
A. Total resistance is less than the smallest resistor.
Less than the resistance of either resistor.
37.3 kilowatts
96 volts.

44. What is the total voltage of eight 12-volt batteries connected in series?
Clean water.
96 volts.
100 ohms
Stays the same.

45. The unit of measurement of power is...
In parallel.
Better speed control on motors.
37.3 kilowatts
Watts.

46. Which current flows in only one direction?
Power.
Direct current.
Voltage.
Current

47. What is the equivalent resistance of two 8-ohm resistors connected in parallel?
Current.
Distance.
Stays the same.
4.0 ohms.

48. What is Ohm's Law?
The movement of electrons in a circuit.
Current that flows in one direction only.
Current
E=IR.

49. Which of the following motors CANNOT be run without a load?
Series-wound.
Until the victim receives medical attention.
Heat
Stays the same.

50. Power is measured with a...
4.8 ohms
Ohms.
Attract each other.
Wattmeter.