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A string is stretched between fixed poin...

A string is stretched between fixed points separated by 75 cm. It is observed to have a resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequences between these two. Then the lowest resonant frequency for this string is :

A

105 Hz

B

1.05 Hz

C

1050 Hz

D

10.5 Hz

Text Solution

Verified by Experts

The correct Answer is:
A
Frequency of 315 Hz and 420 Hz are in the ratio of 3 : 4 . So they are third and fourth harmonics . If `v_(1)` is the fundamental frequency then `v_(3) = 3 v_(1) `
`rArr " " v_(1) = (315)/(3) = `105 Hz.
so correct choice is (a) .
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