Question

Light enters an isosceles right triangular prism at normal incidence through face AB and undergoes total internal reflection at face BC as shown below :
The minimum value of the refractive index of the prifsm is close to:

• A. $1.10$
• B. $1.55$
• C. $1.42$
• D. $1.72$

Answer 1

The correct option is C $1.42$

$n_1=1;n_2=?;{\theta }_1={90}^0;{\theta }_2={45}^0$
using snell's law
$n_{1}sin{\theta }_1=n_{2}sin{\theta }_2$
$n_2=\frac{sin{90}^0}{sin{45}^0}$
$n_2=1.414$
hence,The minimum value of the refractive index of the prism is close to 1.42.