What is a ray?
The word ray has several meanings. One of the most common is the light strip emanating from the light source. It is called so - a ray of light, a ray of sunshine, a ray of searchlight.
But there are several other meanings of this word.
In a more general sense, a beam means the direction of movement of not only light, but also other types of electromagnetic energy, propagating both in the form of waves and in the form of a stream of particles. So, infrared, ultraviolet, x-rays or gamma rays are called, respectively, infrared, ultraviolet, x-rays or gamma rays.
Sometimes they go even further and the beam refers to the direction of propagation of any waves and particle fluxes. In particular, there are concepts of sound or seismic rays. And, for example, in a television picture tube, a cathode emits a beam of electrons, which is often called a cathode ray.
Often the word beam is used in a figurative sense, when a source of light means a different concept, usually positive. For example, they say: a ray of hope, rays of glory.
Finally, in geometry, a beam is a part of a straight line, which consists of the starting point of the beam and all other points lying on one side of it. A beam with a beginning at point A, which contains point B, is denoted by [AB). And, for example, if the beginning of the beam is designated as zero, and the points in equal intervals - with natural numbers, then such a figure can be called a numerical ray.