# Gibilisco: MCQ in Impedance and Admittance | ECE Board Exam

(Last Updated On: March 16, 2020) 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.

### Start Practice Exam Test Questions

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 + j7 and 3 – j7?

• A. 0 + j0
• B. 6 + j14.
• C. -6 – j14.
• D. 0 – j14.

4. What is (-5 + j7) – (4 – j5)?

• A. -1 + j2.
• B. -9 – j2.
• C. -1 – j2.
• D. -9 + j12.

5. What is the product (-4 – j7) (6 – j2)?

• A. 24 – j14.
• B. -38 – j34.
• C. -24 – j14.
• D. -24 + j14.

6. What is the magnitude of the vector 18 – j24?

• A. 42.
• B. -42.
• C. 30.
• D. -30.

7. The impedance vector 5 + j0 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 – j22 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 – j6.0?

• A. Z = 9.0 Ω.
• B. Z = 3.0 Ω.
• C. Z = 45 Ω.
• D. Z = 6.7 Ω.

10. What is the absolute-value impedance of 50 – j235?

• A. Z = 240 Ω.
• B. Z = 58,000 Ω.
• C. Z = 285 Ω.
• D. Z = 185 Ω.

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 Zo 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 Ω, this would most often mean that:

• A. R + jX =100 + j0.
• B. R + jX = 0 + j100.
• C. R + jX = 0 – j100.
• D. You need to know more specific information.

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

• A. j4.79.
• B. –j4.79.
• C. j0. 209.
• D. –j0. 209.

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

• A. –j0.060.
• B. j0.060.
• C. –j17.
• D. j17.

15. Susceptance and conductance add to form:

• A. Impedance.
• B. Inductance.
• C. Reactance.

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

• A. G2 + B2
• B. R2 + X2.
• C. Zo.
• D. Y.

17. Inductive susceptance is measured in:

• A. Ohms.
• B. Henrys.
• 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.