Question 407: Ray Optics

Question

A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is,

Accepted Answer

$$	heta  = {\sin ^{ - 1}}\left( {{1 \over \mu }} ight)$$ = $${\sin ^{ - 1}}\left( {{3 \over 5}} ight)$$
$$ \Rightarrow $$ $$\sin 	heta  = {3 \over 5}$$
$$ 	herefore $$ tan$$	heta $$ = $${3 \over 4}$$ = $${r \over 4}$$
$$ \Rightarrow $$ r = 3 m

Answer

$$\infty $$

Answer

3 m

Answer

6 m

Answer

4 m

Ray Optics

A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is,

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