Question

The refractive index of a certain flint glass is $1.65$. Incident angle is the light reflected from the surface of the glass completely polarized if the glass is immersed in (a) air and (b) water is $(\tan {58.8}^{\circ }=1.65)$ $(\tan {51.1}^{\circ }=1.24)$:

• A. 60${}^{\circ }$, 50 ${}^{\circ }$
• B. 58.8${}^{\circ }$, 51.1${}^{\circ }$
• C. 65${}^{\circ }$, 52${}^{\circ }$
• D. 61${}^{\circ }$, 54${}^{\circ }$

Answer 1

The correct option is B 58.8${}^{\circ }$, 51.1${}^{\circ }$

Incident angle = polarizing angle
$tan\left(i\right)=tan\left(p\right)=\mu =1.65$ when glass is in air
$i=ta{n}^{-1}\left(1.65\right)$
$={58.8}^0$
$tan\left(i\right)=tan\left(p\right)=\frac{1.65}{4/3}$ when glass in water
$i=ta{n}^{-1}\left(\frac{1.65\times 3}{4}\right)$
$=ta{n}^{-1}\left(1.24\right)$
$={55.1}^0.$
So, incident angle are ${58.8}^{0}and{55.1}^0$