There are different types of oscillations in physics, characterized by certain parameters. Consider their main differences, classification according to different factors.
Basic definitions
Under fluctuation is meant a process in which at regular intervals the main characteristics of the movement have the same values.
Periodic oscillations are those in which the values of the basic quantities repeat at regular intervals (oscillation period).
Varieties of oscillatory processes
Let's consider the main types of oscillations that exist in fundamental physics.
Free oscillations are called, which occur in a system that is not subjected to external variable influences after the initial shock.
An example of free oscillation is a mathematical pendulum.
Those types of mechanical vibrations that occur in the system under the action of an external variable force.
Features of classification
By physical nature, the following types of oscillatory movements are distinguished:
- mechanical;
- thermal;
- electromagnetic;
- mixed.
According to the option of interaction with the environment
Types of fluctuations in interaction with the environment are divided into several groups.
Forced oscillations appear in the system under the action of an external periodic action. As examples of this kind of oscillation, we can consider the movement of hands, leaves on trees.
For forced harmonic oscillations, a resonance may appear, in which, with equal values of the frequency of the external influence and the oscillator, with a sharp increase in amplitude.
Own vibrations in the system under the influence of internal forces after it is taken out of equilibrium. The simplest version of free vibrations is the movement of a load that is suspended on a thread or attached to a spring.
Self-oscillations are types in which the system has a certain amount of potential energy used to make oscillations. Their distinguishing feature is the fact that the amplitude is characterized by the properties of the system itself, and not by the initial conditions.
For random fluctuations, the external load has a random value.
Basic parameters of oscillatory movements
All modes of vibration have certain characteristics that should be mentioned separately.
The amplitude is the maximum deviation from the equilibrium position, the deviation of a fluctuating value, it is measured in meters.
Period is the time of one full swing, throughwhich repeats the characteristics of the system, is calculated in seconds.
Frequency is determined by the number of oscillations per unit of time, it is inversely proportional to the oscillation period.
The oscillation phase characterizes the state of the system.
Characteristic of harmonic oscillations
Such types of oscillations occur according to the law of cosine or sine. Fourier managed to establish that any periodic oscillation can be represented as a sum of harmonic changes by expanding a certain function into a Fourier series.
As an example, consider a pendulum with a certain period and cyclic frequency.
What characterizes these types of fluctuations? Physics considers the mathematical pendulum to be an idealized system, which consists of a material point, which is suspended on a weightless inextensible thread, oscillates under the influence of gravity.
Such types of vibrations have a certain amount of energy, they are common in nature and technology.
With prolonged oscillatory motion, the coordinate of its center of mass changes, and with alternating current, the value of current and voltage in the circuit changes.
There are different types of harmonic oscillations by physical nature: electromagnetic, mechanical, etc.
The shaking of a vehicle that moves on a rough road acts as a forced oscillation.
Main differences between forced and freefluctuations
These types of electromagnetic oscillations differ in physical characteristics. The presence of medium resistance and friction forces lead to damping of free oscillations. In the case of forced oscillations, energy losses are compensated by its additional supply from an external source.
The period of a spring pendulum relates the mass of the body and the stiffness of the spring. In the case of a mathematical pendulum, it depends on the length of the thread.
With a known period, you can calculate the natural frequency of the oscillatory system.
In technology and nature, there are fluctuations with different frequency values. For example, the pendulum that oscillates in St. Isaac's Cathedral in St. Petersburg has a frequency of 0.05 Hz, while for atoms it is several million megahertz.
After a certain period of time, damping of free oscillations is observed. That is why forced oscillations are used in real practice. They are in demand in a variety of vibration machines. The vibratory hammer is a shock-vibration machine that is designed for driving pipes, piles, and other metal structures into the ground.
Electromagnetic oscillations
Characterization of modes of oscillation involves the analysis of the main physical parameters: charge, voltage, current strength. As an elementary system, which is used to observe electromagnetic oscillations, is an oscillatory circuit. It is formed by connecting a coil and a capacitor in series.
When the circuit is closed, free electromagneticfluctuations associated with periodic changes in the electric charge on the capacitor and the current in the coil.
They are free due to the fact that when they are performed there is no external influence, but only the energy stored in the circuit itself is used.
If we consider the resistance of the coil to be zero, and take the period of oscillation as T, we can consider one complete oscillation made by the system.
In the absence of external influence, after a certain period of time, the damping of the electromagnetic oscillation is observed. The reason for this phenomenon will be the gradual discharge of the capacitor, as well as the resistance that the coil actually has.
That is why damped oscillations occur in a real circuit. Reducing the charge on the capacitor leads to a decrease in the energy value in comparison with its original value. Gradually, it will be released as heat on the connecting wires and coil, the capacitor will be completely discharged, and the electromagnetic oscillation will be completed.
The importance of fluctuations in science and technology
Any movements that have a certain degree of repetition are oscillations. For example, a mathematical pendulum is characterized by a systematic deviation in both directions from the original vertical position.
For a spring pendulum, one full swing corresponds to its movement up and down from the initial position.
In an electrical circuit that has capacitance and inductance, there is a repetition of charge oncapacitor plates. What is the cause of oscillatory movements? The pendulum functions due to the fact that gravity causes it to return to its original position. In the case of a spring model, a similar function is performed by the elastic force of the spring. Passing the equilibrium position, the load has a certain speed, therefore, by inertia, it moves past the average state.
Electric oscillations can be explained by the potential difference that exists between the plates of a charged capacitor. Even when it is completely discharged, the current does not disappear, it is recharged.
Modern technology uses fluctuations that differ significantly in their nature, degree of repetition, nature, and also the “mechanism” of appearance.
Mechanical vibrations are made by strings of musical instruments, sea waves, a pendulum. Chemical fluctuations associated with a change in the concentration of reactants are taken into account when conducting various interactions.
Electromagnetic oscillations allow the creation of various technical devices, such as telephones, ultrasonic medical devices.
The brightness fluctuations of Cepheids are of particular interest in astrophysics, and scientists from different countries are studying them.
Conclusion
All types of oscillations are closely related to a huge number of technical processes and physical phenomena. Their practical importance is great in aircraft construction, shipbuilding, the construction of residential complexes, electrical engineering, radio electronics, medicine, and fundamental science. An example of a typical oscillatory process inphysiology favors the movement of the heart muscle. Mechanical vibrations are found in organic and inorganic chemistry, meteorology, and many other natural sciences.
The first studies of the mathematical pendulum were carried out in the seventeenth century, and by the end of the nineteenth century, scientists were able to establish the nature of electromagnetic oscillations. The Russian scientist Alexander Popov, who is considered the "father" of radio communications, conducted his experiments precisely on the basis of the theory of electromagnetic oscillations, the results of research by Thomson, Huygens, and Rayleigh. He managed to find a practical application for electromagnetic oscillations, to use them to transmit a radio signal over a long distance.
Academician P. N. Lebedev for many years conducted experiments related to the production of high-frequency electromagnetic oscillations using alternating electric fields. Thanks to numerous experiments related to various types of vibrations, scientists have managed to find areas for their optimal use in modern science and technology.
