Question

Air confined to a tube closed at both ends with movable piston at one of the ends is used to produce standing sound waves inside. If V is speed of sound in air inside and L is length of the tube then condition for resonant frequencies v_n is:

• A. v_n= $\frac{nV}{2L}$, n =1,2,3......
• B. v_n= $\frac{nV}{4L}$ ,n = 1,3,5............
• C. v_n= $\frac{nV}{8L}$, n = 1,5,9...........
• D. A tube closed at both ends does not have any resonant frequencies

Answer 1

Answer: (A)

v_n= $\frac{nV}{2L}$, n =1,2,3......

Answer 2

n$\frac{\lambda}{2}$ = L where n = 1,2,3............

using V = v λ

v = $\frac{nV}{2L}$, n = 1,2,3...........