# NEETS Module 02 Assignment 2: Inductance

(Last Updated On: December 8, 2017)

This is the Textbook Assignment: Chapter 2, “Inductance” from the Module 2 — Introduction to Alternating Current and Transformers in Navy Electricity and Electronics Training Series (NEETS) . If you are looking for a reviewer in Electronics Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

### Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. The property of inductance offers opposition to which of the following quantities?

• A. Constant current
• B. Constant voltage
• C. Changes in current
• D. Changes in voltage

2. What is the symbol for inductance?

• A. L
• B. H
• C. XL
• D. IND

3. What is the unit of measurement for inductance?

• A. Ohm
• B. Rel
• D. Henry

4. If 9 volts are induced in a conductor when the current changes by 4.5 amperes in one second, what is the total inductance of the circuit?

• A. 1.5 henries
• B. 2.0 henries
• C. 13.5 henries
• D. 40.0 henries

5. What physical property is similar to inductance?

• A. Mass
• B. Motion
• C. Velocity
• D. Inertia

6. The difference in potential across a resistor, created by current through the resistor is an example of which of the following forces?

• A. Resistive
• B. Inertia
• C. Inductive
• D. Electromotive

7. When a magnetic field moves through a stationary conductor, the electrons in orbit are affected in what manner?

• A. They are dislodged from orbit
• B. They move closer to their nucleus
• C. They move closer to other orbiting electrons
• D. They bunch up on one side of the nucleus

8. When electrons are moved in a conductor by a magnetic field, a force known by which of the following terms is created?

• A. Voltage
• B. Electromotive
• C. Potential difference
• D. All of these

9. Self-induced emf is also known as what force?

• A. magnetic force
• B. Inertial force
• C. Electromotive force
• D. Counter electromotive force

10. According to Lenz’s Law, the induced emf produced by a change in current in an inductive circuit tends to have what effect on the current?

• A. It aids a rise in current and opposes fall in current
• B. It aids a fall in current and opposes a rise in current
• C. It opposes either a rise or a fall in current
• D. It aids either a rise or fall in current

11. The direction of the induced voltage in an inductor may be found by application of which of the following rules?

• A. The left-hand rule for inductors
• B. The left-hand rule for generators
• C. The right-hand rule for conductors
• D. The right-hand rule for motors

12. The left-hand rule for generators states that the thumb of the left hand points in the direction of motion of the

• A. conductor
• B. magnetic field
• C. generator poles
• D. induced current

13. When source voltage is removed from a current-carrying conductor, a voltage will be induced in the conductor by which of the following actions?

• A. The decreasing voltage
• B. The collapsing magnetic field
• C. The reversal of current
• D. The reversing electrical field

14. The property of inductance is present in which of the following electrical circuits?

• A. An ac circuit
• B. A dc circuit
• C. A resistive circuit
• D. Each of these

15. How are inductors classified?

• A. By core type
• B. By conductor type
• C. By the number of turns
• D. By the direction of the windings on the core

16. Normally, most coils have cores composed of either air or

• A. copper
• B. carbon
• C. soft iron
• D. carbon steel

17. The hollow form of nonmagnetic material found in the center of an air core coil has what purpose?

• A. To focus the magnetic flux
• B. To support the windings
• C. To act as a low resistance path for flux
• D. To serve as a container for the core

18. Which of the following factors will NOT affect the value of inductance of a coil?

• A. Number of coil turns
• B. Diameter of the coil
• C. Conductor tensility
• D. Core materials used

19. When the number of turns is increased in a coil from 2 to 4, the total inductance will increase by a factor of

• A. eight
• B. two
• C. six
• D. four

20. Why do large diameter coils have greater inductance than smaller diameter coils, all other factors being the same?

• A. Large diameter coils have more wire and thus more flux
• B. Large diameter coils have less resistance
• C. Small diameter coils have less resistance
• D. Small diameter coils have large cemfs which oppose current flow

21. If the radius of a coil is doubled, its inductance is increased by what factor?

• A. One
• B. Two
• C. Eight
• D. Four

22. If the length of a coil is doubled while the number of turns is kept the same, this will have (a) what effect on inductance and (b) by what factor?

• A. (a) Decrease, (b) by 1/4
• B. (a) Decrease, (b) by 1/2
• C. (a) Increase, (b) by 2 times
• D. (a) Increase, (b) by 4 times

23. A soft iron core will increase inductance because it has which of the following characteristics?

• A. Low permeability and low reluctance
• B. Low permeability and high reluctance
• C. High permeability and high reluctance
• D. High permeability and low reluctance

24. An increase in the permeability of the core of a coil will increase which of the following coil characteristics?

• A. Magnetic flux
• B. Reluctance
• C. Resistance
• D. Conductance

25. If a coil is wound in layers, its inductance will be greater than that of a similar single-layer coil because of a higher

• A. permeability
• C. reluctance
• D. conductance

26. Regardless of the method used, inductance of a coil can ONLY be increased by increasing what coil characteristic?

• A. Transconductance
• B. Reluctance
• D. Conductance

27. What is the symbol used to denote the basic unit of measurement for inductance?

• A. L
• B. H
• C. I
• D. F

28. What does the Greek letter Delta signify as in "DI" or "Dt"?

• A. The values are constant
• B. The values are average
• C. The values are changing
• D. The values are effective

29. An electrical circuit contains a coil. When the current varies 2.5 amperes in one second, 7.5 volts are induced in the coil. What is the value of inductance of the coil?

• A. 1 henry
• B. 2.2 henries
• C. 3.3 henries
• D. 4 henries

30. An ac electrical current varies 1.5 amperes in one second and is applied to a 10-henry coil. What is the value of the emf induced across the coil?

• A. 1.0 volt
• B. 1.5 volts
• C. 11.5 volts
• D. 15.0 volts

31. If a coil is rated at 10 henries, what is its value in (a) millihenries and (b) microhenries?

• A. (a) 10,000 mH, (b) 10,000,000 μH
• B. (a) 10,000 mH, (b) 1,000,000 μH
• C. (a) 1,000 mH, (b) 1,000,000 μH
• D. (a) 1,000 mH, (b) 100,000 μH

41. One L/R time constant is equal to the time required for the current in an inductor to reach what portion of its maximum value?

• A. 63.2%
• B. 37.8%
• C. 25.2%
• D. 12.8%

42. Maximum current will flow in an LR circuit after a minimum of how many time constants have elapsed?

• A. One
• B. Five
• C. Three
• D. Four

43. The maximum current in an LR circuit is 20 amperes. What total current will be flowing in the circuit at the end of the second time constant of the charge cycle?

• A. 20.0 amperes
• B. 17.3 amperes
• C. 12.6 amperes
• D. amperes

44. Refer to the circuit described in question 43. Circuit current will increase by what amount during the second time constant?

• A. 17.3 amperes
• B. 12.6 amperes
• C. 7.6 amperes
• D. 4.7 amperes

45. An LR circuit has a maximum current of 30 mA. At the end of the first time constant of the discharge cycle, what total current will be flowing in the circuit?

• A. 11 mA
• B. 19 mA
• C. 26 mA
• D. 28 mA

46. An LR circuit contains a 150-ohm resistor and a 2-henry coil. What is the time value of one L/R time constant?

• A. 7.5 seconds
• B. 0.75 seconds
• C. 1.33 seconds
• D. 0.0133 seconds

47. An LR circuit has a time constant of 0.05 second and an inductor with a value of 0.60 henry. What value of resistor is required?

• A. 5 ohms
• B. 12 ohms
• C. 24 ohms
• D. 64 ohms

48. An LR circuit is composed of a coil of 0.5 henry and a 10-ohm resistor. The maximum current in the circuit is 5 amperes. After the circuit is energized, how long will it take for the current to reach maximum value?

• A. 1.0 second
• B. 0.05 second
• C. 0.25 second
• D. 5.0 seconds

49. Inductors experience copper loss for what reason?

• A. Because of flux leakage in the copper core
• B. Because the reactance of an inductor is greater than the resistance of an inductor
• C. Because all inductors have resistance which dissipates power
• D. Because the inertia of the magnetic field must be overcome every time the direction of current changes

50. Copper loss of an inductor can be calculated by the use of which of the following formulas?

• A. P = I2R
• B. P = I2E
• C. P = E/R2
• D. P = I2/R

51. What term applies to the power loss in an iron core inductor due to the current induced in the core?

• A. Iron loss
• B. Heat loss
• C. Hysteresis loss
• D. Eddy-current loss

52. Power consumed by an iron core inductor in reversing the magnetic field of the core is termed as what type of loss?

• A. Iron loss
• B. Heat loss
• C. Hysteresis loss
• D. Eddy-current loss

53. When does mutual inductance occur between inductors?

• A. Whenever eddy-currents do not exist
• B. Whenever the flux of one inductor causes an emf to be induced in another inductor
• C. Whenever the effect of one inductor is aided by another inductor
• D. Whenever the effect of one inductor is opposed by another inductor

54. Mutual inductance between two coils is affected by which of the following factors?

• A. Material of the windings
• B. Physical dimensions of the coils
• C. Direction of the coil windings
• D. Hysteresis characteristics of the coils

55. The coefficient of coupling between two coils is a measure of what factor?

• A. The turns ratio of the coils
• B. The distance between the coils
• C. The relative positive of the coils
• D. The magnetic flux ratio linking the coils

56. Two coils have a coefficient of coupling of 0.7 and are rated at 12 μH and 3 μH respectively. What is their total mutual inductance?

• A. 4.2 μH
• B. 5.2 μH
• C. 7.0 μH
• D. 10.5 μH

57. An electrical circuit contains four non-coupled inductors in a series configuration. The inductors have the following values: 2 μH, 3.5 μH, 6 μH, and 1 μH. What is the total inductance (LT) of the circuit?

• A. 45.0 μH
• B. 42.5 μH
• C. 12.5 μH
• D. 11.5 μH

58. Two inductors of 3.6 μH and 7.3 μH are wired together in series and they aid each other. The mutual inductance for the circuit is 3.6 μH. What is the total inductance (LT) of the circuit?

• A. 17.5 μH
• B. 18.1 μH
• C. 24.8 μH
• D. 34.4 μH

59. An electrical circuit contains three non-coupled inductors of 3.3 μH, 4.5 μH, and 2.0 μH wired in parallel. What is the total inductance of the circuit?

• A. 9.8 μH
• B. 3.6 μH
• C. 0.98 μH
• D. 0.28 μH

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