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

[Electro]

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

 

[Source]

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.

 

[quicknote]

Hello there,

As a fellow scientist, I understand your confusion regarding this physics problem. Let me provide some insights that may help you solve it.

Firstly, the problem is asking about the reflection of light on a glass cube. This means that the light will hit the surface of the cube and some of it will be reflected, while the rest will be transmitted through the cube.

Now, let's break down the problem. The cube has a small spot at its center, and we need to determine which parts of each face must be covered in order to prevent the spot from being seen, regardless of the viewing direction. This implies that the spot is visible when light is reflected off the surface of the cube. Therefore, we need to cover the parts of the cube's faces that would reflect light towards the viewer's direction, effectively blocking the spot from view.

To determine the fraction of the cube's surface that needs to be covered, we need to consider the total surface area of the cube and the area that needs to be covered. This will give us the percentage of the cube's surface that needs to be covered in order to prevent the spot from being seen.

I hope this helps guide you in solving the problem. Remember to consider the properties of light and how it behaves when reflecting off a surface. Good luck!