Waves - Result Question 56

58. Two identical piano wires kept under the same tension T have a fundamental frequency of 600 Hz. The fractional increase in the tension of one of the wires which will lead to occurrence of 6 beats/s when both the wires oscillate together would be

(a) 0.02

(b) 0.03

(c) 0.04

(d) 0.01

[2011M]

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Answer:

Correct Answer: 58. (a)

Solution:

  1. (a) For fundamental mode, f=12Tm

Taking logarithm on both sides, we get logf=log(12)+log(Tμ)

log(12)+12log(Tμ)

or logf=log(12)+12[logTlogμ]

Differentiating both sides, we get

dff=12dTT (as and μ are constants)

dTT=2×dff

Here df=6

f=600Hz

dTT=2×6600=0.02



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