\(\ell_{1}+ e =\frac{\lambda}{4}\)
\(\lambda=\frac{336}{400} \times 100 \,cm =84 \,cm \Rightarrow \frac{\lambda}{4}=21 \,cm\)
\(e =21-20=1 \,cm\)
For third resonance
\(\ell_{3}+ e =\frac{5 \lambda}{4}=105 \,cm \Rightarrow \ell_{3}=104 \,cm\)
$[\,dB$ માં લબ્ધિ $\left.=10 \log _{10}\left(\frac{ P _{ o }}{ P _{i}}\right)\right]$
(હવામાં ધ્વનિની ઝડપ $=330\, ms^{-1}$)