Question

In a closed organ pipe of length 105 cm, standing waves are set up corresponding to third overtone.
What distance from the closed end, a pressure node is formed?

• A. 5 cm
• B. 15 cm
• C. 25 cm
• D. 30 cm

Answer 1

The correct option is B 15 cm

In closed organ pipe of length $105m$.

Pressure node$=$ Displacement antinode.

3rd overtone, $=7^{th}$ harmonic

$=>\frac{7\lambda }{4}=105cm$

$\frac{\lambda }{4}=15cm$

The displacement are at the position,

$=\frac{\lambda }{4},\frac{3\lambda }{4},\frac{5\lambda }{4},\frac{7\lambda }{4}$

$=15cm,45cm,75cm,105cm$

The displacement from the closed end is $15cm$

The correct option is (B).