Among the following everyday materials, through which one does visible light not pass (that is, which material is effectively opaque to light)?

Introduction / Context:
In optics, materials are classified based on how they transmit light. Transparent materials allow most light to pass so that objects can be clearly seen through them, translucent materials allow partial light with blurring, and opaque materials do not allow light to pass through. This simple conceptual question asks you to identify, among familiar objects, which one is effectively opaque to visible light.

Given Data / Assumptions:

• The materials listed are notebook paper, water, a book and sun glasses.
• We are concerned with visible light and normal everyday usage of these objects.
• We assume typical thicknesses, such as a closed book of many pages and regular notebook paper.
• Opaque means that light does not pass through sufficiently for you to see objects behind the material.

Concept / Approach:
Transparent materials, like clean water and many glasses, allow light to pass so that you can see clearly through them. Translucent materials, like thin notebook paper, allow some light to pass but scatter it so that objects behind appear blurred or not visible in detail. Opaque materials, like a closed book with many pages, block light almost completely, preventing you from seeing through them. Sun glasses are designed to reduce the intensity of light but still allow enough light to pass so that you can see. Therefore, among the options, a book is effectively opaque to light.

Step-by-Step Solution:
Step 1: Consider water. Clean water in a glass is transparent; you can easily see objects through it, so light passes through. Step 2: Consider sun glasses. Although they are tinted and darken the view, you can still see through them, which shows they transmit light, making them partially transparent. Step 3: Consider notebook paper. A single sheet of notebook paper allows some light to pass if held against a bright source, but you cannot see clear images behind it, so it is more translucent than fully transparent. Step 4: Consider a closed book made up of many sheets of paper bound together. Step 5: The total thickness and multiple layers of paper in a book block almost all light; you cannot see through a closed book. Step 6: Therefore, among the given materials, the book is effectively opaque to visible light. Step 7: Conclude that light does not pass through a book in the sense of everyday observation.

Verification / Alternative check:
A simple experiment is to place each of the listed objects between your eye and a bright lamp. Through water, you can clearly see the lamp. Through sun glasses, you can still see the lamp but dimmer. Through a single sheet of notebook paper, you see only a glow without a clear image, indicating partial transmission. Through a closed book, the lamp is completely blocked, and no light appears on the far side. This practical test confirms that the book is the opaque object among the options.

Why Other Options Are Wrong:
Notebook paper, though it can block detailed images, allows some light to pass and is better described as translucent rather than completely opaque. Water is a transparent medium that allows light to pass through with minimal scattering, especially when pure and in a thin layer. Sun glasses are designed to transmit light while filtering and reducing its intensity; they are not opaque because you can see through them.

Common Pitfalls:
Students may think of notebook paper as blocking light because it hides text behind it, but careful observation shows that light can still shine through, especially from a bright source. The question asks through which light cannot pass, so you should choose the material that blocks light in a practical sense. Remember that transparency, translucency and opacity refer to the degree of light transmission, not just whether you can read print through the material.

Final Answer:
Among the given options, a Book is effectively opaque and does not allow visible light to pass through.