A light wave travels through three transparent materials of equal thickness. Rank in order, from the highest to lowest, the indices of refraction $n_1, n_2$ and $n_3$.

The frequency of a tuning fork is $256\, Hz$. The velocity of sound in air is $344\, ms^{-1}$. The distance travelled (in $meters$) by the sound during the time in which the tunning fork complete $32$ vibrations is

A stretched string resonates with tuning fork frequency $512\; Hz$ when length of the string is $0.5\; m$. The length of the string required to vibrate resonantly with a tuning fork of frequency $256 \;Hz$ would be .......... $m$

A device used for investigating the vibration of a fixed string or wire is

The string of a violin has a frequency of $440 \,cps$. If the violin string is shortened by one fifth, its frequency will be changed to ........... $cps$

Two similar sonometer wires given fundamental frequencies of $500Hz$. These have same tensions. By what amount the tension be increased in one wire so that the two wires produce $5$ beats/sec .... $\%$