Show that all harmonics are present in case of a stretched string.
Q.16 Show that all harmonics are present in case of a stretched string.
Q.16 Show that all harmonics are present in case of a stretched string.
Best answer
Answer:
Consider a string of length \(L\), stretched with tension \(T\), of linear density \(m\), fixed at both ends. The speed of transverse waves on it is \(v = \sqrt{T/m}\). When it is plucked, stationary waves are formed with nodes at both fixed ends.
The distance between two successive nodes is \(\lambda/2\), so the length must contain a whole number \(p\) of loops:
\[L = p\frac{\lambda}{2} \Rightarrow \lambda = \frac{2L}{p}\qquad (p = 1, 2, 3, \dots)\]Frequency of the \(p^{th}\) mode:
\[n_p = \frac{v}{\lambda} = \frac{p\,v}{2L} = \frac{p}{2L}\sqrt{\frac{T}{m}}\]Since \(p\) can take every integer value, the frequencies are \(n, 2n, 3n, 4n, \dots\): both odd and even multiples of the fundamental are possible. Hence all harmonics are present in a stretched string.
Log in or create a free account to answer this question.