The optical density of turpentine is higher than that of water,while its mass density is lower. The figure shows a layer of turpentine floating over water in a container. For which of the four rays incident on the turpentine as shown in the figure,is the path correct?

When a ray of light passes from one medium to another,which quantity remains constant?

When light is refracted from a surface, which of its following physical parameters does not change?

$A$ ray of light travelling in air has wavelength $\lambda$,frequency $n$,velocity $v$,and intensity $I$. If this ray enters into water,then these parameters are $\lambda'$,$n'$,$v'$,and $I'$ respectively. Which relation is correct from the following?

$A$ light ray undergoes refraction from air to water,water to glass,and finally from glass back to air. If the emergent ray is parallel to the incident ray,which of the following relations is correct? ($n_{a}, n_{w}, n_{g}$ represent the refractive indices of air,water,and glass respectively.)

In the figure below,$PQRS$ denotes the path followed by a ray of light as it travels through three media in succession. The absolute refractive indices of the media are $\mu_1, \mu_2$ and $\mu_3$,respectively. (The line segment $RS$ in the figure is parallel to $PQ$). Then,