Images formed by an object placed between two plane mirrors whose reflecting surfaces make an angle of $90°$ with one another lie on a

A ray of light from a denser medium strikes a rare medium as shown in figure. The reflected and refracted rays make an angle of $90°$ with each other. The angles of reflection and refraction are $r$ and $r^{\text{'}}$. The critical angle would be

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