$A$ ray of light strikes a glass plate at an angle of $60^o$. If the reflected and refracted rays are perpendicular to each other,the index of refraction of the glass is:

The refractive indices of glass and water with respect to air are $3/2$ and $4/3$ respectively. The refractive index of glass with respect to water will be

If a wave gets refracted into a denser medium,then which of the following is true?

$A$ tank is filled with water to a height of $12.5 \;cm$. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be $9.4 \;cm$. What is the refractive index of water?
If water is replaced by a liquid of refractive index $1.63$ up to the same height,by what distance would the microscope have to be moved to focus on the needle again?

If the wavelength of light in air is $4200\, \mathring A$,what will be the wavelength of light in water $(\mu = 4/3)$ in $\mathring A$?

In the figure given below,a ray of light travelling in a medium of refractive index $\mu$ passes through two different connected rectangular blocks of refractive indices $\mu_1$ and $\mu_2$ $(\mu_2 > \mu_1)$. The angle of incidence $\theta_1$ is increased slightly. Then,the angle $\theta_2$ is