1.

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 :

Answer»

105 Hz
1.05 Hz
1050 Hz
10.5 Hz

Solution :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) = `105HZ.
so correct choice is (a) .


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