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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