 Inductive Reactance – Gibilisco MCQs in Electronics

(Last Updated On: December 8, 2017) This is the Multiple Choice Questions (MCQs) in Chapter 13: Inductive Reactance from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

Start Practice Exam Test Questions

1. As the number of turns in a coil increases, the current in the coil will eventually:

• A. Become very large.
• B. Stay the same.
• C. Decrease to near zero.
• D. Be stored in the core material.

2. As the number of turns in a coil increases, the reactance:

• A. Increases.
• B. Decreases.
• C. Stays the same.
• D. Is stored in the core material.

3. As the frequency of an ac wave gets lower, the value of XL for a particular coil:

• A. Increases.
• B. Decreases.
• C. Stays the same.
• D. Depends on the voltage.

4. A coil has an inductance of 100 mH. What is the reactance at a frequency of 1000 Hz?

• A. 0.628 Ω.
• B. 6.28 Ω.
• C. 62.8 Ω.
• D. 628 Ω.

5. A coil shows an inductive reactance of 200 Ω at 500 Hz. What is its inductance?

• A. 0.637 H.
• B. 628 H.
• C. 63.7 mH.
• D. 628 mH.

6. A coil has an inductance of 400 μH. Its reactance is 33 Ω. What is the frequency?

• A. 13 kHz.
• B. 0.013 kHz.
• C. 83 kHz.
• D. 83 MHz.

7. An inductor has XL = 555 Ω at f = 132 kHz. What is L?

• A. 670 mH.
• B. 670 μH.
• C. 460 mH.
• D. 460 μH.

8. A coil has L = 689 μH at f =990 kHz. What is XL?

• A. 682 Ω.
• B. 4.28 Ω.
• C. 4.28 K Ω.
• D. 4.28 M Ω.

9. An inductor has L = 88 mH with XL = 100 Ω. What is f?

• A. 55.3 kHz.
• B. 55.3 Hz.
• C. 181 kHz.
• D. 181 Hz.

10. Each point in the RL plane:

• A. Corresponds to a unique resistance.
• B. Corresponds to a unique inductance.
• C. Corresponds to a unique combination of resistance and inductive reactance.
• D. Corresponds to a unique combination of resistance and inductance.

11. If the resistance R and the inductive reactance XL both vary from zero to unlimited values, but are always in the ratio 3:1, the points in the RL plane for all the resulting impedances will fall along:

• A. A vector pointing straight up.
• B. A vector pointing “east.”
• C. A circle.
• D. A ray of unlimited length.

12. Each impedance R + jXL:

• A. Corresponds to a unique point in the RL plane.
• B. Corresponds to a unique inductive reactance.
• C. Corresponds to a unique resistance.
• D. All of the above.

13. A vector is a quantity that has:

• A. Magnitude and direction.
• B. Resistance and inductance.
• C. Resistance and reactance.
• D. Inductance and reactance.

14. In an RL circuit, as the ratio of inductive reactance to resistance, XL/R, decreases, the phase angle:

• A. Increases.
• B. Decreases.
• C. Stays the same.
• D. Cannot be found.

15. In a purely reactive circuit, the phase angle is:

• A. Increasing.
• B. Decreasing.
• C. 0 degrees.
• D. 90 degrees.

16. If the inductive reactance is the same as the resistance in an RL circuit, the phase angle is:

• A. 0 degrees.
• B. 45 degrees.
• C. 90 degrees.
• D. Impossible to find; there’s not enough data given.

NOTE: For questions 17 – 18 see Fig.13-14. 17. In Fig. 13-14, the impedance shown is:

• A. 8.0.
• B. 90.
• C. 90 + j8.0.
• D. 8.0 + j90.

18. In Fig. 13-14, note that the R and XL scale divisions are of different sizes. The phase angle is:

• A. About 50 degrees, from the looks of it.
• B. 48 degrees, as measured with a protractor.
• C. 85 degrees, as calculated trigonometrically.
• D. 6.5 degrees, as calculated trigonometrically.

19 An RL circuit consists of a 100-μH inductor and a 100-Ω resistor. What is the phase angle at a frequency of 200 kHz?

• A. 45.0 degrees.
• B. 51.5 degrees.
• C. 38.5 degrees.
• D. There isn’t enough data to know.

20. An RL circuit has an inductance of 88 mH. The resistance is 95 Ω. What is the phase angle at 800 Hz?

• A. 78 degrees.
• B. 12 degrees.
• C. 43 degrees.
• D. 47 degrees.