This is the Multiple Choice Questions (MCQs) in Chapter 15: Impedance and Admittance 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. The square of an imaginary number:

- A. Can never be negative.
- B. Can never be positive.
- C. Might be either positive or negative.
- D. Is equal to
*j*.

2. A complex number:

- A. Is the same thing as an imaginary number.
- B. Has a real part and an imaginary part.
- C. Is one-dimensional.
- D. Is a concept reserved for elite imaginations.

3. What is the sum of 3 + *j*7 and 3 - *j*7?

- A. 0 +
*j*0 - B. 6 +
*j*14. - C. -6 -
*j*14. - D. 0 -
*j*14.

4. What is (-5 + *j*7) - (4 - *j*5)?

- A. -1 +
*j*2. - B. -9 -
*j*2. - C. -1 -
*j*2. - D. -9 +
*j*12.

5. What is the product (-4 - *j*7) (6 - *j*2)?

- A. 24 -
*j*14. - B. -38 -
*j*34. - C. -24 -
*j*14. - D. -24 +
*j*14.

6. What is the magnitude of the vector 18 - *j*24?

- A. 42.
- B. -42.
- C. 30.
- D. -30.

7. The impedance vector 5 + *j*0 represents:

- A. A pure resistance.
- B. A pure inductance.
- C. A pure capacitance.
- D. An inductance combined with a capacitance.

8. The impedance vector 0 - *j*22 represents:

- A. A pure resistance.
- B. A pure inductance.
- C. A pure capacitance.
- D. An inductance combined with a resistance.

9. What is the absolute-value impedance of 3.0 - *j*6.0?

- A.
*Z*= 9.0 Î©. - B.
*Z*= 3.0 Î©. - C.
*Z*= 45 Î©. - D.
*Z*= 6.7 Î©.

10. What is the absolute-value impedance of 50 - *j*235?

- A.
*Z*= 240 Î©. - B.
*Z*= 58,000 Î©. - C.
*Z*= 285 Î©. - D.
*Z*= 185 Î©.

11. If the center conductor of a coaxial cable is made to have smaller diameter, all other things being equal, what will happen to the *Z*o of the transmission line?

- A. It will increase.
- B. It will decrease.
- C. It will stay the same.
- D. There is no way to know.

12. If a device is said to have an impedance of *Z *= 100 Î©, this would most often mean that:

- A.
*R*+*j*X =100 +*j*0. - B.
*R*+*j*X = 0 +*j*100. - C.
*R*+*j*X = 0 -*j*100. - D. You need to know more specific information.

13. A capacitor has a value of 0.050 Î¼F at 665 kHz. What is the capacitive susceptance?

- A.
*j*4.79. - B. -
*j*4.79. - C.
*j*0. 209. - D. -
*j*0. 209.

14. An inductor has a value of 44 mH at 60 Hz. What is the inductive susceptance?

- A. -
*j*0.060. - B.
*j*0*.*060. - C. -
*j*17. - D.
*j*17.

15. Susceptance and conductance add to form:

- A. Impedance.
- B. Inductance.
- C. Reactance.
- D. Admittance.

16. Absolute-value impedance is equal to the square root of:

- A.
*G*2 +*B*2 - B.
*R*2 +*X*2. - C.
*Z*o. - D.
*Y*.

17. Inductive susceptance is measured in:

- A. Ohms.
- B. Henrys.
- C. Farads.
- D. Siemens.

18. Capacitive susceptance is:

- A. Positive and real valued.
- B. Negative and real valued.
- C. Positive and imaginary.
- D. Negative and imaginary.

19. Which of the following is false?

- A.
*BC*= 1/*XC*. - B. Complex impedance can be depicted as a vector.
- C. Characteristic impedance is complex.
- D.
*G*= 1/*R*.

20. In general, the greater the absolute value of the impedance in a circuit:

- A. The greater the flow of alternating current.
- B. The less the flow of alternating current.
- C. The larger the reactance.
- D. The larger the resistance.

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