Question

Light rays from a luminous (bright point) object in a denser medium of refractive index n at a depth h, outline a circle of radius equal to the depth, at the interface. The refractive index of denser medium is

• A. 1.51
• B. 1.61
• C. 1.41
• D. 1.8

Answer 1

Answer: (C)

1.41

Answer 2

Apply Snell;s law at the interface, $n \sin \theta c = (1) \sin 90^{\circ}$
or $\frac{r}{\sqrt{r^2 + h^2}} = \frac{1}{n}$
Here, $r = h$
So, $\frac{r}{r \sqrt{2}} = \frac{1}{n} \, \, \, \, \, \therefore \, n = \sqrt{2} = 1.41$