Question

The length of two open organ pipes are l and ( l + $\Delta l)$ respectively. Neglecting

end correction, the frequency of beats between them will be approximately

(Here v is the speed of sound)

[MP PET 1994; BHU 1995]

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

${\lambda }_1=2l,{\lambda }_2=2l+2\Delta l\Rightarrow n_1=\frac{v}{2l}and{n}_2=\frac{v}{2l+2\Delta l}$
The difference of $n_1$ and $n_2$ will be equal to $\frac{v\Delta l}{2l^2}$