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標題:

F.4 Maths( log )

發問:

A cassette player is playing at a sound intensity level of 55 dB. If the sound intensity increases by 8 dB, find the % increase of the sound intensity.

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最佳解答:

Let A = reference sound intensity B = original sound intensity C = new sound intensity so 55 = 10 log B/A = 10 log B - 10 log A ..........(1) and (55 + 8) = 10 log C/A = 10 log C - 10 log A ...........(2) (2) - (1) we get 8 = 10 log C - 10 log B 8= 10 log C/B so C/B = 10^0.8 = 6.3 % increase = (C - B)/B x 100% = 530%.

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