2020 Phase-2 WavesVibration of strings - fundamental frequency and length Medium Question 10 of 59 in Waves

The length of the string of a musical instrument is 90 cm and has a fundamental frequency of 120 Hz. Where should it be pressed to produce fundamental frequency of 180 Hz?

A 80 cm
B 75 cm
C 60 cm
D 45 cm

The answer is C.

Solution

For a stretched string, fundamental frequency $f\propto\dfrac{1}{l}$ (same tension and mass per unit length), so $f_1l_1=f_2l_2\Rightarrow120\times90=180\times l_2\Rightarrow l_2=60$ cm.

Concept Vibration of strings - fundamental frequency and length

Waves in past papers

59 questions from this chapter have appeared across 25 exam years.