P18_088 - threshold is 10 12 = I 2 /I 1 . Thus, with r 2 =...

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88. The source being a “point source” means A sphere =4 πr 2 is used in the intensity defnition I = P/A , which Further implies I 2 I 1 = P/ 4 πr 2 2 P/ 4 πr 2 1 = µ r 1 r 2 2 . ±rom the discussion in § 18-5, we know that the intensity ratio between “barely audible” and the “painFul
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Unformatted text preview: threshold is 10 12 = I 2 /I 1 . Thus, with r 2 = 10000 m, we fnd r 1 = r 2 10 12 = 0 . 01 m....
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