Question

Consider the case of normal modes of vibration for the air column with only one end closed. What is the length of the air column for the fundamental harmonic?

(a) λ/2

(b) λ

(c) 2λ

(d) λ/4

Answer 1

Right answer is (d) λ/4

The best I can explain: For the given condition wavelength is related to length by: λ = 4L/(2n+1).

∴ For fundamental harmonic n=0, & L = (2n+1)λ/4

= (0 + 1)λ/4

= λ/4.