Wave Optics Ques 1
1. The Brewsters angle $\mathrm{i}_{\mathrm{b}}$ for an interface should be
[2020]
(a) $30^{\circ}<\mathrm{i}_{\mathrm{b}}<45^{\circ}$
(b) $45^{\circ}<$ i $_{\text {b }}<90^{\circ}$
(c) $\mathrm{i}_{\mathrm{b}}=90^{\circ}$
(d) $0^{\circ}<\mathrm{i}_{\mathrm{b}}<30^{\circ}$
Show Answer
Answer:
Correct Answer: 1.(b)
Solution: (b) According to Brewster’s law, when a beam of unpolarised light is reflected from a transparent medium of refractive index $\left(\mu_2\right)$, the reflected light is completely polarised at certain angle of incidence called the angle of polarisation $\left(i_b\right)$.
$ \begin{aligned} & \tan i_b=\frac{\mu_2}{\mu_1} \\ & \text { For air, } \mu_1=1 \\ & \therefore \tan i_b=\mu_2>1 \\ & \Rightarrow \tan i_b>1 \Rightarrow 90^{\circ}>i_b>45^{\circ} \end{aligned} $
BETA
