In a large telecommunications auditorium, perforated absorbent materials are used to line the ceiling so as to
Increase the reverberation of sound in the hall
increase the amount of echo in the hall
reduce the hight of the ceiling from the floor
reduce the reverberation of sound in the hall
Explanation
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Discussions (3)
The answer **B. I, III, and IV only** is incorrect because of statement **I**.
- **I. They should be identical**: This is incorrect. For two waves to interfere, they don't have to be identical. For example, waves with different amplitudes or intensities can still interfere.
While **III (They should be coherent)** and **IV (They should be monochromatic)** are correct, the inclusion of **I** makes option B wrong.
Therefore, the correct answer remains **C. II, III, and IV only**.
The correct answer is **C. II, III, and IV only**.
Explanation:
- **I. They should be identical**: This is incorrect because waves do not need to be identical to interfere. They can have different amplitudes, for example.
- **II. They should originate from the same source**: This is correct. For interference to occur, the waves must be coherent, which is more likely if they come from the same source or have a constant phase difference.
- **III. They should be coherent**: This is correct. Coherent waves have a constant phase difference, which is essential for sustained interference patterns.
- **IV. They should be monochromatic**: This is correct. Monochromatic waves (having the same frequency) are required for interference patterns to be clear and stable.
Hence, the correct conditions are II, III, and IV.
