A) 1.9 m
B) 1.8 m
C) 2.0 m
D) 2.1 m
E) 3.2m
Correct Answer: D
Solution :
Suppose, nth harmonic of frequency 420 Hz equals to (n + 1) th harmonic of 490 Hz. then \[420=\frac{n}{2l}\sqrt{\frac{T}{\mu }}\] ?(i) and \[490=\frac{n+1}{2l}\sqrt{T/\mu }\] ...(ii) On dividing Eq. (ii) by Eq. (i), we get \[\frac{490}{420}=\frac{n+1}{n}\] \[\Rightarrow \] \[n=6\] On putting \[n=6\]in Eq (i), we get \[420=\frac{6}{2l}\sqrt{\frac{450}{5\times {{10}^{-3}}}}\Rightarrow L=\frac{900}{420}=2.1\,m\]You need to login to perform this action.
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