A string is stretched between two fixed points separated by $75\,cm$ . It is observed to have resonant frequencies of $420\,Hz$ and $315\,Hz$ . There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is  ..... $Hz$

A $1 cm$ long string vibrates with fundamental frequency of $256\, Hz$. If the length is reduced to $\frac{1}{4}cm$ keeping the tension unaltered, the new fundamental frequency will be

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

Two wires are producing fundamental notes of the same frequency. Change in which of the following factors of one wire will not produce beats between them

A sonometer wire oflength $1.5\ m$ is made of steel. The tension in it produces an elastic strain of $1 \%$. What is the fundamental frequency of steel if density and elasticity of steel are $7.7 \times 10^3 $ $kg/m^3$ and $2.2 \times 10^{11}$ $N/m^2$ respectively?

What will be the change in phase of wave due to reflection from rigid support ?