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                                    A string in a musical instrument is `50 cm` long and its fundanmental frequency is `800 Hz` If the frequency of `1000 Hz` is to be produced then required length of spring isA. `37.5 cm`B. `40 cm`C. `50 cm`D. `62.5 cm` | 
                            
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Answer» Correct Answer - b The frequency producted in a string of length of L mass per unit length m , and tension T is `n = (1)/(2l) sqrt((T)/(m))` Given `l_(1) = 50 cm , n_(1) = 800 Hz` M and `n_(2) = 1000 Hz` `:. (n_(1))/(n_(2)) = (l_(2))/(l_(1))` `rArr l_(2) = (n_(1)l_(1))/(n_(2)) = (800 xx 50)/(100) = 40 cm`  | 
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