Question

Light is going from some denser medium to air. The refractive index of the medium is 1.7. Calculate the angle of incidence, such that if it is further increased, total internal reflection will occur in medium I.

• A. $si{n}^{-1}\left(\frac{1}{\sqrt{3}}\right)$
• B. $si{n}^{-1}\left(\frac{1}{\sqrt{2}}\right)$
• C. $si{n}^{-1}\left(\frac{1}{\sqrt{5}}\right)$
• D. Such an angle of incidence can't be calculated

Answer 1

The correct option is A $si{n}^{-1}\left(\frac{1}{\sqrt{3}}\right)$


That angle must be the criticle angle.
$\frac{sin\theta }{sin.{90}^{\circ }}=\frac{1}{1.7}$
$\therefore \theta =si{n}^{-1}\left(\frac{1}{\sqrt{3}}\right)$