Answer:
The diameter of the circle at the surface is 1.814 m.
Explanation:
Given that,
Depth = 80 cm
Let the critical angle be c.
From Snell's law
[tex]sin c=\dfrac{1}{n}[/tex]
[tex]c=sin^{-1}\dfrac{1}{n}[/tex]
The value of n for water,
[tex]n = \dfrac{4}{3}[/tex]
Put the value of n in the equation (I)
[tex]c =sin^{-1}\dfrac{3}{4}[/tex]
[tex]c=48.6^{\circ}[/tex]
We know that,
[tex]tan c=\dfrac{r}{h}[/tex]
We calculate the radius of the circle
[tex]r =h tan c[/tex]
[tex]r=80\times10^{-2}\times\tan48.6^{\circ}[/tex]
[tex]r =0.907\ m[/tex]
The diameter of the circle at the surface
[tex]d =2\times r[/tex]
[tex]d =2\times 0.907[/tex]
[tex]d =1.814\ m[/tex]
Hence, The diameter of the circle at the surface is 1.814 m.
