Question

Critical angle of glass is ${\theta }_1$ and that of water is ${\theta }_2$. The critical angle for water and glass surface would be $({\mu }_g=\frac{3}{2},{\mu }_w=\frac{4}{3})$.

• A. less than ${\theta }_2$
• B. between ${\theta }_1$ and ${\theta }_2$.
• C. greater than ${\theta }_2$
• D. less than ${\theta }_1$

Answer 1

Answer: (C)

greater than ${\theta }_2$

$\mu -\frac{{\mu }_w}{w_g}=9$

IC$={\sin }^{-1}\frac{1}{\mu }$

$={\sin }^{-1}\frac{8}{9}$

Now, since

${\sin }^{-1}\frac{8}{9}>{\sin }^{-1}\frac{2}{3}$

${\sin }^{-1}\frac{8}{9}>{\sin }^{-1}\frac{3}{4}$

$\Rightarrow greaterthan{\theta }_2$