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.
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