$A$ person lives in a high-rise building at a height of $30 \ m$ on the bank of a river. Across the river is a well-lit tower of height $60 \ m$. When the person looks through a polarizer at an appropriate angle at light from the top of the tower reflecting from the river surface,he finds the intensity of light is least. If the refractive index of water is $\frac{4}{3}$,the width of the river is ...... $m$.

$A$ person lives in a high-rise building on the bank of a river $50\, m$ wide. Across the river is a well-lit tower of height $40\, m$. When the person,who is at a height of $10\, m$,looks through a polarizer at an appropriate angle at light of the tower reflecting from the river surface,he notes that the intensity of light coming from a distance $X$ from his building is the least,and this corresponds to the light coming from light bulbs at height $Y$ on the tower. The values of $X$ and $Y$ are respectively close to (refractive index of water $\simeq \frac{4}{3}$)

$A$ ray of light is incident from a denser to a rarer medium. The critical angle for total internal reflection is $\theta_{iC}$ and Brewster's angle of incidence is $\theta_{iB}$,such that $\sin \theta_{iC} / \sin \theta_{iB} = \eta = 1.28$. The relative refractive index of the two media is

The angle of polarisation for a medium is $60^o$. What will be the critical angle for this medium?

Unpolarized light of intensity $I_0$ is incident on the surface of a block of glass at Brewster's angle. In that case,which one of the following statements is true?

At what angle should an unpolarised beam be incident on a crystal of $\mu = \sqrt{3}$,so that the reflected beam is polarised (in $^{\circ}$)?