How come light only reflects off surfaces and not internal planes?

In summary, light is reflected from all planes when it enters a material, but the deeper it goes, the less light is left due to absorption. The front and back planes of atoms have a special role in reflection because they are close to the surface. This is why many x-ray spectrometers use Bragg diffraction off these planes. Similarly, sound only reflects off boundaries between different media because the effect of reflection is much greater than scattering in the bulk of the material. This difference is significant enough to ignore in most cases.
  • #1
jeebs
325
4
When light approaches and enters a material, why does all the reflection happen at the surfaces? I mean, light is coming at say, some crystalline solid. It hits the first plane of atoms and some is reflected. Some goes into the crystal and passes through the 2nd, 3rd, 4th,..., (n-1)th plane of atoms completely unreflected. Then it hits the far boundary (the nth) plane of atoms and some gets reflected. What is so special about the front and back planes of atoms?
 
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  • #2
Light gets reflected from all the planes. Only the deeper it is, the less light there is left because of absorption, or skin depth. For a metal, this layer is very thin, so only the planes near the surface are relevant.
 
  • #3
Many x-ray spectrometers use Bragg diffraction (or reflection), nλ = 2d sin(θ), off the crystal planes; quartz 310, silicon 111, among others.

Bob S
 
  • #4
ahh Bragg diffraction of course, I remember that...
 
  • #5
There tends to be greater light reflection at boundaries between different media where there is a change of refractive index.
 
  • #6
Analogously - why does sound only reflect off the walls, not each "layer" of atmosphere it's traveling through?

Part 1 - It does.

Part 2 - The effect of reflection from an impedance boundary is vastly greater than the effect of scatter in the bulk of the material. The difference is sufficient to ignore for almost all applications.
 

FAQ: How come light only reflects off surfaces and not internal planes?

1. Why does light only reflect off surfaces?

Light is made up of tiny particles called photons. When these photons hit a surface, they bounce off in different directions. This is known as reflection. However, when light enters an object, the photons are absorbed and scattered, making it impossible for them to reflect off internal planes.

2. How does the angle of incidence affect the reflection of light?

The angle at which light hits a surface, known as the angle of incidence, determines the angle at which it will reflect. According to the law of reflection, the angle of incidence is equal to the angle of reflection. This is why we see reflections at different angles depending on the position of the light source and the observer.

3. Why do different surfaces reflect light differently?

The ability of a surface to reflect light is determined by its texture, composition, and angle of the surface. Smooth and shiny surfaces, such as mirrors, reflect light more efficiently than rough and dull surfaces. This is because rough surfaces cause light to scatter in different directions, making it harder to see a clear reflection.

4. Can light reflect off internal planes under certain conditions?

Yes, there are certain materials such as mirrors and glass that can reflect light off internal planes. This is because they are made up of highly reflective surfaces that are able to bounce the photons off multiple times, creating the appearance of a reflection from within the material.

5. Why is it important to understand the behavior of light when it comes to reflection?

Understanding the behavior of light when it comes to reflection is crucial in many fields, including optics, photography, and engineering. It allows us to manipulate and control the direction of reflected light, which is essential in creating various devices such as telescopes, cameras, and solar panels. Additionally, the study of light reflection helps us understand how we perceive our surroundings and how light interacts with different materials.

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