الطاقة المشعة - الطاقة الكهربائية .. الفيزياء

Radiant Energy - Electrical Energy .. Physics

Radiant Energy

We have seen that most forms of energy that we have known so far depend on the atoms and molecules of matter in their transmission. However, it is possible to transmit energy through space without the need for pipes, wires or any form of matter. The energy emitted in this way is called radiant energy and is composed of electromagnetic waves. Talking about energy waves that probe the depths of space is somewhat difficult to imagine, but we can comprehend them if we imagine a swimming pool floating on the surface of its still water and near its edge is a matchbox. If a small stone falls in the middle of the pool, circular waves emanate from the point of its fall towards the edge, causing the matchbox to be raised and lowered periodically. In this case, the energy required for the movement of the matchbox is derived from the kinetic energy generated by the falling stone, which was transferred to the matchbox by waves traveling on the surface of the water in all directions. Electromagnetic waves are very similar to water waves, with one very important difference: they do not need a substance to move them from one place to another, and like water waves they take the form of alternating peaks and valleys. All waves are characterized by four properties: amplitude, wavelength, frequency, and propagation speed.

The peak of the wave's movement, and the wavelength is the distance between two successive peaks, while the frequency is the number of complete cycles that occur in the amplitude per second.

Electromagnetic rays travel in space at a tremendous speed that does not change, and the relationship that links the frequency of the wave. The speed of light (in Hertz) is called the distance it travels per second, which is as follows: d = n A, where l represents the wavelength.

The wavelength ranges from 10.5 meters to 10-17 meters. Long waves, i.e. low-frequency waves, are used in radio and television broadcasting, and if their frequency increases slightly, they become known as heat waves. If it rises further, the retina becomes sensitive to it and is called light waves. As for the high frequencies, they are ultraviolet rays, X-rays, and gamma rays. The highest frequency known to man is the frequency of waves that reach us from distant space, and are called cosmic rays.

(Opposite page) The electromagnetic spectrum.
(Left) The transfer of energy by waves on the surface of water (Right) Characteristics of a traveling wave.