Question Detail

PHY 104 Pitch, loudness, quality, timber Objective Question
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Question

Based on the provided solution in the problem section, if the sound source is at P and the distances to points A, B, and C are effectively 5m, 3m, and 9m respectively, what is the ratio of sound intensity at A, B, and C (IA : IB : IC)?
Options
A 25 : 9 : 81
B 729 : 2025 : 225
Correct Answer
C 1/5 : 1/3 : 1/9
D 9 : 3 : 5
Correct Answer

Option B is the correct answer.

Detailed Explanation

The problem solution in the text states: 'IA : IB : IC = k/52 : k/32 : k/92 = 1/25 : 1/9 : 1/81'. To get integer ratios, we find the least common multiple of 25, 9, 81 (which is 2025*9=18225) and multiply by it: (18225/25) : (18225/9) : (18225/81) = 729 : 2025 : 225. This matches the provided solution.

Hint

Remember the inverse-square law (I ∝ 1/r²) and convert the fractional ratio to whole numbers as shown in the text's solution.

Question Info

Course: PHY 104
Topic: Pitch, loudness, quality, timber
Type: Objective
Difficulty: Not specified
Question 470 of 947
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