What determines how light is reflected

[Sea Cow]

What is it exactly about a surface that makes it reflect or absorb some or all wavelengths of light?

 

[ZapperZ]

What is it exactly about a surface that makes it reflect or absorb some or all wavelengths of light?

1. the presence of conduction electrons
2. the nature of the phonon modes in the material

Zz.

 

[Andy Resnick]

Alternatively, the index of refraction.

 

[Sea Cow]

1. the presence of conduction electrons
2. the nature of the phonon modes in the material

Zz.

Forgive me if I am being thick, but could you explain point 2. more? What is it about the phonon modes? For instance, if a surface just reflects a particular colour, is that because the phonon vibrates at the same frequency as that colour? If so, how does that stop the light from being absorbed?

Thankyou for your patience.

 

[PJC01]

The reflectivity of a surface is determined by its physical and chemical properties. The surface's texture, smoothness, and composition all play a role in how light is reflected. For example, a smooth and polished surface will reflect more light compared to a rough and uneven surface.

The reflectivity of a surface is also dependent on its color. Different colors absorb and reflect different wavelengths of light. For instance, a red surface appears red because it absorbs all colors of light except for red, which it reflects back to our eyes.

The atomic and molecular structure of a surface also plays a crucial role in its reflectivity. A surface with a dense and tightly packed structure will reflect more light compared to a surface with a looser and more porous structure.

Furthermore, the angle at which light hits a surface also affects its reflectivity. The law of reflection states that the angle of incidence (incoming light) is equal to the angle of reflection (reflected light). The smoother the surface, the more parallel the incoming and reflected light will be, resulting in a higher reflectivity.

In summary, the reflectivity of a surface is determined by a combination of its physical and chemical properties, color, and structure, as well as the angle of incident light. Understanding these factors is crucial in various fields, such as optics, materials science, and photography.