A string is stretched between fixed points separated by 75 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is
10.5 Hz
105 Hz
1.05 Hz
1050 Hz.
As we learnt in
Vibration of composite string when joint is a node (N) -
- wherein
are number of loops in two cases
are length of two parts
are linear density in two parts
Let the successive loops formed be P and (P+1) for frequencies 315 Hz and 420 Hz
p = 1 for fundamental mode of vibration of string.
Lowest resonant frequency = 105 Hz.
Correct option is 2.
Option 1)
10.5 Hz
This is an incorrect option.
Option 2)
105 Hz
This is the correct option.
Option 3)
1.05 Hz
This is an incorrect option.
Option 4)
1050 Hz.
This is an incorrect option.
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