Question

A standing wave is produced in a vibrating string in its third harmonic as shown in the figure. If the length of the string is 1.5m and the frequency of the vibrating motor is 60Hz. Find out the speed of the wave ?

• A. 15 m/s
• B. 20 m/s
• C. 40 m/s
• D. 60 m/s
• E. 90 m/s

Answer 1

Answer: (D)

60 m/s

Given : $\nu =60$ Hz $L=1.5$ m

According to figure, wavelength of the standing wave $\lambda =\frac{2}{3}L=\frac{2}{3}\times 1.5=1.0$ m

Thus speed of the wave $v=\lambda \times \nu =1.0\times 60=60$ m/s