Question

Three successive resonant frequencies in a closed organ pipe are 825Hz, 1155Hz and 1485Hz. If speed of sound in air is 330 m/s then the wrong statement is: 

(a) Fundamental frequency of the pipe is 165Hz

(b) Length of the pipe is 0.5m

(c) Frequency of first overtone is 495Hz

(d) Frequency of first harmonic is 330Hz

Answer 1

The correct option (d) Frequency of first harmonic is 330Hz

Explanation:

825 = 165 x 5, 1155 = 165 x 7 and 1485 = 165 x 9 

Therefore 825Hz is 5^th harmonic and fundamental frequency of the pipe is, n₀ = 165Hz. 

First overtone will be n₁ = 3n₀ = 495Hz and first harmonic will be n₀ = 165Hz