The rms velocity of a gas molecules oí mass $m$ at a given temperature is proportional to

The speed of a wave on a string is $150 \mathrm{~ms}^{-1}$ when the tension is 120 N . The percentage increase in the tension in order to raise the wave speed by $20 \%$ is

The minimum deviation produced by a hollow prism filled with a certain liquid is found to be $30^{\circ}$. The light ray is also, found to be refracted at an angle of $30^{\circ}$. Then, the refractive index of the liquid is

In Young's double slit experiment, the intensity at a point where the path difference is $\frac{\lambda}{6}$ ( $\lambda$ being the wavelength of the light used) is $I$. If $I_0$ denotes the maximum intensity, $\frac{I}{I_0}$ is equal to