Question

A closed organ pipe of length $1.2m$ vibrates in its first overtone mode. The pressure variation is maximum at

• A. 0.4 m from the open end
• B. 0.4 m from the closed end
• C. Both (a) and (b)
• D. 0.8 m from the open end

Answer 1

Answer: (A)

In first overtone mode
$l=\frac{3\lambda }{4}$
$\therefore \frac{\lambda }{4}=\frac{l}{3}$

$=\frac{1.2}{3}=0.4m$
Pressure variation will be maximum at displacement nodes, ie, at $0.4m$ from the open end.