The lengths of the two organ pipes open at both ends are $L$ and $(L+L_1)$. If they are sounded together,the beat frequency will be ($v=$ velocity of sound in air).

$A$ closed pipe of length $300 \,cm$ contains some sand. $A$ speaker is connected at one of its ends. The frequency of the speaker at which the sand will arrange itself in $20$ equidistant piles is close to .......... $kHz$ (velocity of sound is $300 \,m/s$).

When an air column in a pipe open at both ends vibrates such that four antinodes and three nodes are formed,then the corresponding mode of vibration is

$A$ tuning fork of frequency $480\, Hz$ is used in an experiment for measuring the speed of sound $(\nu)$ in air by the resonance tube method. Resonance is observed to occur at two successive lengths of the air column,$\ell_1 = 30\, cm$ and $\ell_2 = 70\, cm$. Then $\nu$ is equal to ..... $m/s$.

Two open organ pipes of lengths $50 \,cm$ and $51 \,cm$ are totally immersed in a medium. They are found to give $40$ beats in $10 \,s$ when each is sounding at its fundamental note. The speed of sound in this medium is (in $\,ms^{-1}$)

An organ pipe with both ends open has a length $L=25 \,cm$. An extra hole is created at position $\frac{L}{2}$. The lowest frequency of sound produced is (assume, speed of sound $=340 \,m/s$) (in $\,Hz$)