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.

### Begin the Test

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 Î©.
- B. 6.28 Î©.
- C. 62.8 Î©.
- D. 628 Î©.

5. A coil shows an inductive reactance of 200 Î© 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 Î¼H. Its reactance is 33 Î©. What is the frequency?

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

7. An inductor has *XL *= 555 Î© at *f *= 132 kHz. What is *L?*

- A. 670 mH.
- B. 670 Î¼H.
- C. 460 mH.
- D. 460 Î¼H.

8. A coil has *L *= 689 Î¼H at *f *=990 kHz. What is *XL*?

- A. 682 Î©.
- B. 4.28 Î©.
- C. 4.28 K Î©.
- D. 4.28 M Î©.

9. An inductor has *L *= 88 mH with *XL *= 100 Î©. 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 +
*j*8.0. - D. 8.0 +
*j*90.

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-Î¼H inductor and a 100-Î© 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 Î©. What is the phase angle at 800 Hz?

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

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