Oscillation, as a category of physical concepts, is one of the basic concepts of physics and is defined, in general terms, as a repeating process of changing a certain physical quantity. If these changes are repeated, then this means that there is a certain period of time through which the physical quantity takes the same value. This period of time is called the period of oscillation.
But actually, why the fluctuations? Yes, because if we fix the value of this quantity, say at time T1, then at time Tx it will take on a different value, say, increase, and after a while it will increase again. But the increase cannot be eternal, because for a repeating process, there will come a moment when this physical quantity must repeat itself, i.e. will again take on the same value as at the moment T1, although on the time scale it is already the moment T2.
What has changed? Time. One time period has passed, which will be repeated as the time distance between the same values of a physical quantity. But what happened to the physical quantity over this period of time - the period? It's okay, she just made one hesitation - she went through the full cycle of her changes - from maximum to minimum. If in the process of changing from T1 to T2 time was fixed, then the difference T = T2-T1 gives a numerical expression of the time period.
A good example of an oscillatory process is a spring pendulum. The weight moves up and down, the process repeats, and the value of a physical quantity, for example, the height of the pendulum, fluctuates between the maximum and minimum values.
The description of the oscillation process includes universal parameters for oscillations of any nature. It can be mechanical, electromagnetic vibrations, etc. It is always important to understand that the oscillatory process for its existence necessarily includes two objects, each of which can receive and / or give energy - this is the same mechanical or electromagnetic one that was discussed above. At each moment of time, one of the objects gives off energy, and the second receives. At the same time, energy changes its essence to something very similar, but not so. So, the energy of the pendulum, passes into the energy of a compressed spring, and they periodically change during the process of oscillation, solving the eternal question of partnership - who should raise and lower whom, i.e. give or accumulate energy.
Electromagnetic vibrations already in the name contain an indication of the alliance members - an electric and magnetic field, and the well-known capacitor and inductance serve as custodians of these fields. Connected into an electric circuit, they represent an oscillatory circuit in which energy is pumped in exactly the same way as in a pendulum — the electric energy of the capacitor passes into the magnetic field of the inductance and vice versa.
If the capacitor-inductance system is left to its own devices and electromagnetic oscillations arise in it, then their period is determined by the parameters of the system, i.e. inductance and capacitance - there are no others. Simply put, in order to "transfer" energy from a source, say, a capacitor (and there is also a more accurate analogue of its name - "capacitance"), inductance, you need to spend time proportional to the amount of stored energy, i.e. capacity. In fact, the magnitude of this “capacity” is the parameter on which the period of oscillations depends. More capacity, more energy - the energy transfer lasts longer, the period of electromagnetic oscillations is longer.
What physical quantities are included in the set that defines the description of the electromagnetic field in all its manifestations, including during oscillatory processes? These are the components of the field: charge, current, magnetic induction, voltage. It should be noted that electromagnetic oscillations are a wide range of phenomena that we, as a rule, rarely connect with each other, although this is the same essence. And how do they differ? The first difference between any fluctuations among themselves is their period, the essence of which was considered above. In engineering and science, it is customary to talk about the reciprocal of the magnitude, the frequency - the number of oscillations per second. The system unit for measuring frequency is hertz.
So, the whole scale of electromagnetic oscillations is a sequence of frequencies of electromagnetic radiation that propagate in space.
The following sections are conventionally distinguished:
- radio waves - spectral band from 30 kHz to 3000 GHz;
- infrared rays - a section of a longer wavelength than light;
- visible light;
- ultraviolet rays - a section of a shorter wavelength than light radiation;
- X-rays;
- gamma rays.
The entire range of emissions is electromagnetic radiation of a single nature, but of different frequencies. The breakdown into sections is purely utilitarian in nature, which is dictated by the convenience of technical and scientific applications.