A point source is emitting sound waves of intensity \( 16 \times 10^{-8}\ \text{W}\ \text{m}^{-2} \) at the origin. The difference in intensity (magnitude only) at two points located at a distance of \( 2\,\text{m} \) and \( 4\,\text{m} \) from the origin respectively will be ______ \( \times 10^{-8}\ \text{W}\ \text{m}^{-2} \).
In a closed organ pipe, the frequency of fundamental note is \( 30 \, \text{Hz} \). A certain amount of water is now poured in the organ pipe so that the fundamental frequency is increased to \( 110 \, \text{Hz} \). If the organ pipe has a cross-sectional area of \( 2 \, \text{cm}^2 \), the amount of water poured in the organ tube is ______ \( \text{g} \). (Take speed of sound in air is \( 330 \, \text{m/s} \))
