Physics (AS & A Level) · May / June 2016 · Paper 43 · Question 4
9702
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4(a)(i)[2]
product of speed and density reference to speed in medium (and density of medium) [2]
4(a)(ii)[2]
α: ratio of reflected intensity and/to incident intensity Z1 and Z2: (specific) acoustic impedances of media (on each side of boundary) B1 [2]
4(b)[5]
in muscle: IM = I0 e–µx = I0 exp(–23 × 3.4 × 10–2) IM / I0 = 0.457 at boundary: α = (6.3 – 1.7) 2 / (6.3 + 1.7) 2 = 0.33 IT /IM = [(1 – α) =] 0.67 IT / I0 = 0.457 × 0.67 = 0.31 [5]
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