Q.

In a resonance tube with tuning fork of frequency 512 Hz, first resonance occurs at water level equal to 30.3 cm and second resonance occurs at 63.7 cm. The maximum possible error in the speed of sound is                       [2005]

1 51.2 cm/s  
2 102.4 cm/s  
3 204.8 cm/s  
4 153.6 cm/s  

Ans.

(3)

In a resonance tube,

1+e=λ4                           2+e=3λ4

But v=νλ

  v=ν43(2+e)            2+e=3v4ν             ...(i)

  v=ν4(1+e)             1+e=v4ν               ...(ii)

Subtracting (i) and (ii),

v=2ν(2-1)

 Δv=2ν(Δ2+Δ1)

=2×512×(0.1+0.1) cm/s

=204.8 cm/s

Hence, maximum possible error in speed, Δv=204.8 cm/s