We explain what reflection is in physics, differences with refraction and various examples. Also, what is a personal reflection.
Reflection occurs when waves come into contact with a surface.What is reflection?
In physical, a reflection is called phenomenon abrupt change of direction experienced by certain waves (as the light or the sound), when coming into contact with the separation surface of two different and changing media, and which causes part of the waves to return to the medium from which they came.
More easily said, a portion of the waves is returned when they hit the surface of a different medium, as occurs when light hits a mirror, losing a good part of their Energy. Thus, studying the nature of the impacted surface, it is possible to predict the margin of change of direction of the waves, applying simple calculations trigonometric.
Thus, there are two types of reflection:
- Regular or specular reflection. It occurs when the impacted surface is smooth and regular, and the waves undergo a change of direction without changing the propagation medium.
- Diffuse reflection. It occurs when the impacted surface is rough or irregular, and therefore the waves are not reflected in any direction, but rather diffuse.
Reflection is a very common optical phenomenon in everyday life and well known since ancient times, whose understanding has allowed the design of different technologies and applications in industry.
Reflection and refraction
Refraction occurs because the speed of propagation of the waves depends on the medium.The phenomenon of reflection is usually studied together with that of refraction, the latter consists in that, when passing from a propagation medium to a slower one, the physical waves experience a certain margin of distortion, which gives rise to different apparent phenomena.
This is what happens, for example, when we insert a spoon into a glass of water, and we observe that the submerged portion and the portion in the air seem not to coincide or to be discontinuous: an optical illusion caused by the refraction of light in the water. .
Refraction is explained by the Snell-Descartes law, which proposes a mathematical formula to calculate the angle of refraction of an electromagnetic wave when penetrating from one medium to another that have different refractive index, that is, different physical properties. This is because the speed of propagation of the waves alters according to the medium they pass through.
In this way, reflection and refraction are forms of alteration of the propagation of physical waves, but while the first involves the "bouncing" of the waves on the surface of a medium, the second occurs when the waves actually penetrate the environment. another medium and their propagation capacities are altered.
Examples of light reflection
Some examples of light reflection are as follows:
- The flashes of the sunlight on the walls, when they hit the polished screen of a cell phone or a wristwatch.
- The possibility of seeing ourselves in a mirror, whose highly polished surface allows the beams of light to be returned to our eyes.
- The very existence of colors It occurs due to reflection: white light impacts all things, and these reflect only certain wavelengths (the others are absorbed) that are captured by our eyes.
- The colors and shapes that are seen on the surface of a soap bubble, the result of the reflection of light on the delicate surface of the bubble.
Personal reflection
There is another possible meaning of the word reflection that has nothing to do with physics, but that comes from the same etymological root: the Latin word you reflect, composed by re ("Backwards") and flectere ("Bend" or "deflect"). Thus, "reflecting" would be "bending back", and in a figurative sense, it implies looking back at the weather, that is, to think about what happened, to see what happened already, that is, to reflect.
Obviously, a reflection is not necessarily a review of the past, but it can also consist of an anticipation of the future or an investigation of the present, but in any case it always has the meaning of a deep thought or a review (that is, “to return to see ”) of things in any area.