Question

A string is firmly attached at both ends. When a frequency of 60 Hz is applied, the string vibrates in the standing wave pattern shown. Assume the tension in the string and its mass per unit length do not change. Which of the following frequencies could NOT also produce a standing wave pattern in the string?

A) 30 Hz 

B) 40 Hz 

C) 80 Hz 

D) 100 Hz 

E) 180 Hz

Answer 1

The correct option is: (A) 30 Hz 

Explanation:

The given diagram is the 3rd harmonic at 60 Hz. That means the fundamental is 20Hz. The other possible standing waves should be multiples of 20.