Dear Aimen,

The following publications cover the answer to your question:

Regarding the first part of the question "Why does light reflect from mirror-like surfaces? " Please see the following text"

What is the Law of Reflection of Light? - Definition & Overview

Chapter 8 / Lesson 25 

http://study.com/academy/lesson/what-is-the-law-of-reflection-of-light-definition-lesson-quiz.html

Definition

Have you ever wondered why you are able to see your reflection in a mirror or why you see things reflected in the first place? An even more important question is why do we even see a table, or a chair or our phones sitting on the table? The answer to these questions happens to be one of the simplest laws in physics; it is called the law of reflection.

The Law of Reflection states that the angle of the incident light ray is equal to the angle of the reflected light ray. To understand what these angles and light rays stand for, consider the following diagram depicting the law of reflection. In this depiction, the blue band represents a mirror, which reflects rays of light.

 Law of Reflection Illustrated

 The most important thing about the law of reflection is shown as a dashed line in the figure labeled thenormal. The normal line is just a line drawn to the surface of the mirror that makes a 90 degree angle to the mirror. This line is used a reference point for all of the angles in the law of reflection.

The incident ray is the beam of light that initially strikes the mirror and the reflected ray is the beam of light that bounces off the mirror after striking the mirror. The angle of incidence is the angle that the incident ray makes with the normal and the angle of reflection, or reflected angle, is the angle that the reflected ray makes with the normal. The equation for the law of reflection is given by the following formula:

 The angle of incidence equals the ray of reflection.

 So this law states that any ray of light that strikes an object will reflect off the object such that the striking or incident angle is identical to the reflecting angle (as measured from the normal).

More on Reflection

The law of reflection tells us that light reflects from objects in a very predictable manner. So the question is, why do we see objects like a table or a chair? These objects do not produce their own light, so in order for us to see any object, light must strike the object and reflect from the object into our eyes. More specifically, in order for us to be able to see objects, the light reflecting off an object must make its way directly to our eyes. So how does the light get from the object to our eyes? It does so through one of the two types of reflection: specular and diffuse reflection.

Specula Reflection

Specular reflection is reflection off smooth surfaces. We can think of a beam of light as being composed of a bundle of many rays of light. When the beam hits a smooth surface like a mirror or a still pond, the rays collectively travel together with the same intensity and undisturbed. The figure below illustrates specular reflection.

 Specular Reflection: Reflecting off a Smooth Surface

 Let's say you are driving at night on a wet road. The light from your headlights hits the wet road and reflects back at you in an annoying glare. Specular reflection is responsible for the glare. The water on the road creates a smooth surface for the light to reflect off, and since the light bundle travels together with the same intensity, the glare reflects back at you, impairing your vision. Another example of specular reflection is illustrated in the image below.

 Specular Reflection: The body of water acts like a mirror

 A perfect mirror image is created by the body of water, which acts like a gigantic mirror and enables specular reflection.

Regarding the second part of the question "is there a reflection of light when the light passes through a nanofluids? and Why " Please read the following paper:

JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY 3, 023104 2011

http://scitation.aip.org/content/aip/journal/jrse/3/2/10.1063/1.3571565

Concentrated solar energy has become the input for an increasing number of experimental and commercial thermal systems over the past 10–15 years [M. Thirugnanasambandam et al. , Renewable Sustainable Energy Rev.14 (2010)]. Recent papers have indicated that the addition of nanoparticles to conventional working fluids (i.e., nanofluids) can improve heat transfer and solar collection [H. Tyagi et al. , J. Sol. Energy Eng.131, 4 (2009); P. E. Phelan et al. , Annu. Rev. Heat Transfer14 (2005)]. This work indicates that power tower solar collectors could benefit from the potential efficiency improvements that arise from using a nanofluid working fluid. A notional design of this type of nanofluid receiver is presented. Using this design, we show a theoretical nanofluid enhancement in efficiency of up to 10% as compared to surface-based collectors when solar concentration ratios are in the range of 100–1000. Furthermore, our analysis shows that graphite nanofluids with volume fractions on the order of 0.001% or less are suitable for 10–100 MWe power plants. Experiments on a laboratory-scale nanofluid dish receiver suggest that up to 10% increase in efficiency is possible (relative to a conventional fluid)—if operating conditions are chosen carefully. Lastly, we use these findings to compare the energy and revenue generated in a conventional solar thermal plant to a nanofluid-based one. It is found that a 100 MWe capacity solar thermal power tower operating in a solar resource similar to Tucson, AZ, could generate ∼$3.5 million more per year by incorporating a nanofluid receiver.

Hoping this will be helpful,

Rafik

Dear Rafik

Thank you for your reply. Actually I know all what you mentioned above. But my question is" Why". Why reflection occurs? What happens to the photons to be reflected? Why these photons don't be absorbed, for example?

Actually I am looking for an interpretation not to a description.

Aimen Zeiny

I know its too late but it might help.

Physical basics that interpret all light scattering (including reflection, refraction and diffraction) and absorption in explained in detail in this book.

''Absorption and scattering of light by small particles'' by Craig F. Bohren, Donald R. Huffman.

Here is a small paragraph in its introduction section:

''Everything except a vacuum is heterogeneous in some sense. Even in media that we usually consider to be homogeneous( e g , pure gases, liquids, or solids) it is possible to distinguish the individual heterogeneities (atoms and molecules) with a sufficiently fine probe. Therefore, all media scatter light. In fact, many phenomena that are not usually referred to as scattering phenomena are ultimately the result of scattering. Among these are: (1) diffuse reflection by rough surfaces; (2) diffraction by slits, gratings, and edges; and (3) specular reflection and refraction at optically smooth interfaces''