A ray is one of the geometric concepts. Etymology and origin of the word

The words that we use appear to us familiar, familiar from childhood and understandable. It seems to us that we always know what we are talking about and what we mean. But if you try to find out from any passer on the street, for example, the meaning of the word "ray", you can hardly expect a quick and correct answer. Indeed, and what is it?

Etymology of the word

Let's look at the beginning with the origin of this word. According to the dictionary of the Russian language, a ray is a stream of light that comes from some source, or a narrow band of light emanating from a glowing object. For example, the rays of the setting or rising sun.

The exact origin of the term is unknown, but, presumably, it originates from the Latin word "light". In Slavic languages this word is found everywhere. In Russian it fell into their Old Slavonic.

Value and scope

The word "ray" primarily evokes associations with sunlight. How many times have everyone heard the expression: "sunbeams" or "ray of light". But in fact this word has a direct relation to geometry. A ray is a part of a straight line, which is bounded on one side by a point, and on the other by an infinite one.

Any ray has an extreme point. This is the beginning of the ray. Since it does not have an end, it is usually denoted by one letter. In addition, the beam is one of the simplest geometric figures, such as a segment or a broken line.

The concept of a ray is also used in physics, but only in acoustics and geometrical optics. Here the ray is the line along which the light energy moves.

The main feature of the geometric and light ray is their straightness. But for light it is true only if it is distributed in a homogeneous transparent environment. Otherwise it becomes curvilinear.

How to see the light

This experience will be very pleasant for children, it will visually show them what a ray of light is. This requires simple preparations. You need to darken the room and put on the edge of the table any flashlight. A ray of light is now barely visible, but it is only necessary to squeeze a previously prepared plastic bottle with talc or baby powder, like particles of powder, after getting into it, they begin to glow. Now children can see that the light ray is a strip of light emanating from a flashlight and continuing into infinity. Why is this happening? The fact is that light can not be seen until it is reflected from some surface. Particles of talc, hitting a ray of light, make it well visible.