A tunning fork of frequency \( 340\,\text{Hz} \) resonates in the fundamental mode with an air column of length \( 125\,\text{cm} \) in a cylindrical tube closed at one end. When water is slowly poured in it, the minimum height of water required for observing resonance once again is ____________ \( \text{cm} \).
(Velocity of sound in air is \( 340\,\text{ms}^{-1} \))
