Reflection of Light: Solving Physics Problem on Glass Cube Surface Coverage

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The physics problem involves determining which parts of a solid glass cube's faces need to be covered to obscure a central spot from all viewing angles. The cube has a refractive index of 1.5 and measures 10 mm on each edge. The challenge lies in understanding how light refraction affects visibility, as the spot may be hidden from some angles but visible from others. The goal is to identify the necessary surface coverage to ensure the spot remains unseen regardless of the observer's position. Ultimately, the discussion seeks clarity on the implications of the problem and how to calculate the required surface area coverage.
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Hello to all,
I have a physics problem regarding reflection of light.

A solid glass cube, of edge 10 mm and n = 1.5 has a small spot at its center. a) What parts of each cube face must be covered to prevent the spot from being seen, no matter what the direction of viewing? b) What fraction of the cube surface must be covered?

The point is that I don't get what the problem is implying. Anyone can give a hint or just a startup clue?
Thank You
 
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When viewed from certain angles, the spot would not be visible due to bending (refraction) of light; however, the spot would be visible at certain other points. It's asking what must be 'blacked out,' so to speak, in order for the spot never to be seen from the areas where refraction wouldn't prevent it from being seen, and then, what fraction (how much) of the surface area must be covered.
 

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