A large glass slab (µ = 5/3) of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius R cm. What is the value of R?

Engineering

Physics

Plane Surface Refraction

Total Internal Reflection

Question

A large glass slab (µ = 5/3) of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius R cm. What is the value of R?

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$\sin θ_{c} = \frac{1}{n} = \frac{3}{5}$

$θ_{c} = 37 °$

$\frac{R}{8} = {tanθ}_{c} = \frac{3}{4}$

R = 6 cm