why are strings of different thicknesses and materials used in a sitar

1.	why are strings of different thicknesses and materials used in a sitar or a violin ?
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :Fundamental frequency of streched string `v= 1/2L sqrt T/m`. when we use string of <a href="https://interviewquestions.tuteehub.com/tag/defferent-2048560" style="font-weight:bold;" target="_blank" title="Click to know more about DEFFERENT">DEFFERENT</a> thiknesses and materials, they have different values of <a href="https://interviewquestions.tuteehub.com/tag/mass-1088425" style="font-weight:bold;" target="_blank" title="Click to know more about MASS">MASS</a> as <a href="https://interviewquestions.tuteehub.com/tag/per-590802" style="font-weight:bold;" target="_blank" title="Click to know more about PER">PER</a> unit length (m). So the strings will <a href="https://interviewquestions.tuteehub.com/tag/produced-592947" style="font-weight:bold;" target="_blank" title="Click to know more about PRODUCED">PRODUCED</a> notes of different frequencies.</body></html>

why are strings of different thicknesses and materials used in a sitar or a violin ?