The Brewster angle for the glass-air interface is $54.74^{\circ} .$ If a ray of light going from air to glass strikes at an angle of incidence $45^{\circ}$, then the angle of refraction is (Hint: $\left.\tan 54.74^{\circ}=\sqrt{2}\right)$

The polarising angle for transparent medium is $\mathrm{\theta }; v$ is the speed of light in that medium. Then the relation between $\mathrm{\theta }$ and $v$is ($c$ is velocity of light in air) 

Light is incident at an angle $i$ on a glass slab. The reflected ray is completely polarised. The angle of refraction is 

The relation between the polarising angle and the critical angle is 

The angle of polarisation for any medium is $60^{\circ} .$ What will be the critical angle for this?

A ray of light travelling in impure water is incident on a glass plate immersed in it. When the angle of incidence is $51^{\circ},$ the reflected ray is totally plane polarised. Given that refractive index of impure water is $1.4 .$ The refractive index of glaiss should be $\quad\left(\tan 51^{\circ}=1.235\right)$

If the shift of wavelength of light emitted by a star is towards violet, then this shows that star is,