This is the Multiple Choice Questions (MCQs) in Chapter 12: Phase 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. Which of the following is *not *a general characteristic of an ac wave?

- A. The wave shape is identical for each cycle.
- B. The polarity reverses periodically.
- C. The electrons always flow in the same direction.
- D. There is a definite frequency.

2. A sine wave:

- A. Always has the same general appearance.
- B. Has instantaneous rise and fall times.
- C. Is in the same phase as a cosine wave.
- D. Rises very fast, but decays slowly.

3. The derivative of a sine wave:

- A. Is shifted in phase by 1⁄2 cycle from the sine wave.
- B. Is a representation of the rate of change.
- C. Has instantaneous rise and fall times.
- D. Rises very fast, but decays slowly.

4. A phase difference of 180 degrees in the circular model represents:

- A. 1/4 revolution.
- B. 1/2 revolution.
- C. A full revolution.
- D. Two full revolutions.

5. You can add or subtract a certain number of degrees of phase to or from a wave, and end up with exactly the same wave again. This number is:

- A. 90.
- B. 180.
- C. 270.
- D. 360.

6. You can add or subtract a certain number of degrees of phase to or from a sine wave, and end up with an inverted (upside-down) representation of the original. This number is:

- A. 90.
- B. 180.
- C. 270.
- D. 360.

7. A wave has a frequency of 300 kHz. One complete cycle takes:

- A. 1⁄300 second.
- B. 0.00333 second.
- C. 1⁄3,000 second.
- D. 0.00000333 second.

8. If a wave has a frequency of 440 Hz, how long does it take for 10 degrees of phase?

- A. 0.00273 second.
- B. 0.000273 second.
- C. 0.0000631 second.
- D. 0.00000631 second.

9. Two waves are in phase coincidence. One has a peak value of 3 V and the other a peak value of 5 V. The resultant will be:

- A. 8 V peak, in phase with the composites.
- B. 2 V peak, in phase with the composites.
- C. 8 V peak, in phase opposition with respect to the composites.
- D. 2 V peak, in phase opposition with respect to the composites.

10. Shifting the phase of an ac sine wave by 90 degrees is the same thing as:

- A. Moving it to the right or left by a full cycle.
- B. Moving it to the right or left by 1⁄4 cycle.
- C. Turning it upside-down.
- D. Leaving it alone.

11. A phase difference of 540 degrees would more often be spoken of as:

- A. An offset of more than one cycle.
- B. Phase opposition.
- C. A cycle and a half.
- D. 1.5 Hz.

12. Two sine waves are in phase opposition. Wave *X *has a peak amplitude of 4 V and wave *Y *has a peak amplitude of 8 V. The resultant has a peak amplitude of:

- A. 4 V, in phase with the composites.
- B. 4 V, out of phase with the composites.
- C. 4 V, in phase with wave
*X*. - D. 4 V, in phase with wave
*Y*.

13. If wave *X *leads wave *Y *by 45 degrees of phase, then:

- A. Wave
*Y*is 1⁄4 cycle ahead of wave*X*. - B. Wave
*Y*is 1⁄4 cycle behind wave*X*. - C. Wave
*Y*is 1⁄8 cycle behind wave*X*. - D. Wave
*Y*is 1⁄16 cycle ahead of wave*X*.

14. If wave *X *lags wave *Y *by 1⁄3 cycle, then:

- A.
*Y*is 120 degrees earlier than*X*. - B.
*Y*is 90 degrees earlier than*X*. - C.
*Y*is 60 degrees earlier than*X.* - D.
*Y*is 30 degrees earlier than*X.*

**NOTE: For questions 15 see Fig.12-12.**

15. In the drawing of Fig. 12-12:

- A.
*X*lags*Y*by 45 degrees. - B.
*X*leads*Y*by 45 degrees. - C.
*X*lags*Y*by 135 degrees. - D.
*X*leads*Y*by 135 degrees.

**NOTE: For questions 16 - 20 see Fig.12-13.**

16. Which of the drawings in Fig. 12-13 represents the situation of Fig. 12-13?

- A. A.
- B. B.
- C. C.
- D. D.

17. In vector diagrams such as those of Fig. 12-13, length of the vector represents:

- A. Average amplitude.
- B. Frequency.
- C. Phase difference.
- D. Peak amplitude.

18. In vector diagrams such as those of Fig. 12-13, the angle between two vectors represents:

- A. Average amplitude.
- B. Frequency.
- C. Phase difference.
- D. Peak amplitude.

19. In vector diagrams such as those of Fig. 12-13, the distance from the center of the graph represents:

- A. Average amplitude.
- B. Frequency.
- C. Phase difference.
- D. Peak amplitude.

20. In diagrams like those of Fig. 12-13, the progression of time is sometimes depicted as:

- A. Movement to the right.
- B. Movement to the left.
- C. Rotation counterclockwise.
- D. Rotation clockwise.

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