On a glass plate,a light wave is incident at an angle of $60^o$. If the reflected and the refracted waves are mutually perpendicular,the refractive index of the material is:

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

An observer can see through a pinhole,the top end of a thin rod of height $h$,placed as shown in the figure. The beaker's height is $3h$ and its radius is $h$. When the beaker is filled with a liquid up to a height $2h$,he can see the lower end of the rod. Then the refractive index of the liquid is

$A$ tank is filled with water to a height of $16 \text{ cm}$. Find the apparent depth of a needle lying at the bottom of the tank as measured by a microscope. The refractive index of water $(\mu_{w})$ is $\frac{4}{3}$. (in $\text{ cm}$)

$A$ ray of light passes from vacuum into a medium of refractive index $n$. If the angle of incidence is twice the angle of refraction,then the angle of incidence in terms of refractive index is

If the angle of incidence is twice the angle of refraction in a medium of refractive index $\mu$,then the angle of incidence is