Question

Values for Brewster's angle can be

• A. only less than $45^{\circ}$
• B. only greater than $45^{\circ}$
• C. any value in the range $0^{\circ}$ to $90^{\circ}$ except $45^{\circ}$
• D. any value in the range $0^{\circ}$ to $90^{\circ}$ including $45^{\circ}$

Answer 1

Answer: (C)

Brewster's angle corresponding to two media of refractive indices $r_{1}$ and $r_{2}$ is
$\tan i_{B}=\left(\frac{n_{2}}{n_{1}}\right)$
Where, $n_{2}$ is refractive index of denser medium and $n_{1}$ is refractive index of rarer medium. If two mediums are same,
i.e. $n_{1}=n_{2} \Rightarrow \tan i_{B}=1$ or $i_{B}=45^{\circ}$
Polarisation is not possible if two mediums are same.
Therefore $i_{B} \neq 45^{\circ}$
Hence, Brewster's angle can have any value in the range $0^{\circ}$ to $90^{\circ}$ except $45^{\circ}$.