There are different types of oscillations in physics, characterized by certain parameters. Consider their main differences, classification by various factors.
Key Definitions
By oscillation is meant a process in which, at equal intervals of time, the basic characteristics of the movement have the same values.
Periodic oscillations are called oscillations in which the values of the basic quantities are repeated at regular intervals (oscillation period).
Varieties of oscillatory processes
Consider the main types of vibrations that exist in fundamental physics.
Free are called vibrations that occur in a system that is not exposed to external variable influences after the initial shock.
As an example of free oscillations is a mathematical pendulum.
Those types of mechanical vibrations that occur in the system under the influence of an external variable force.
Classification Features
By their 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 distinguish several groups.
Forced oscillations appear in the system under the action of an external periodic action. As examples of this type of vibrations, you can consider the movement of the hands, leaves on the trees.
For forced harmonic oscillations, the appearance of a resonance is possible, in which for equal values of the frequency of the external action and the oscillator with a sharp increase in amplitude.
These are natural vibrations in the system under the influence of internal forces after it is removed from the equilibrium state. The simplest option for free vibrations is the movement of the load, which is suspended on a thread, or attached to a spring.
Self-oscillations are called species in which the system has a certain supply of potential energy, which goes to commit 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.
The main parameters of oscillatory movements
All types of vibrations have certain characteristics, which should be mentioned separately.
Amplitude is the maximum deviation from the equilibrium position, the deviation of an oscillating quantity, it is measured in meters.
The period is the time of one complete oscillation, through which the characteristics of the system are repeated, calculated in seconds.
The frequency is determined by the number of oscillations per unit time, it is inversely proportional to the period of oscillations.
The oscillation phase characterizes the state of the system.
Characteristic of harmonic oscillations
These types of oscillations occur according to the law of cosine or sine. Fourier was able to establish that any periodic oscillation can be represented as the sum of harmonic changes by expanding a certain function in a Fourier series.
As an example, we can consider a pendulum having a certain period and a cyclic frequency.
What is characterized by such types of vibrations? Physics considers the mathematical pendulum 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 continuous 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 vibrations by their physical nature: electromagnetic, mechanical, etc.
The shaking of a vehicle that moves along an uneven road acts as a forced oscillation.
The main differences between forced and free vibrations
These types of electromagnetic waves differ in physical characteristics. The presence of medium resistance and friction forces lead to the damping of free vibrations. In the case of forced oscillations, energy losses are compensated by its additional supply from an external source.
The period of the 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 oscillations with different frequencies. For example, the pendulum, which oscillates in St. Isaac's Cathedral in St. Petersburg, has a frequency of 0.05 Hz, and for atoms it is several million megahertz.
After a certain period of time, damping of free vibrations is observed. That is why forced oscillations are used in real practice. They are in demand in a variety of vibrating machines. The vibratory hammer is a shock-vibration machine, which is designed to drive pipes, piles, and other metal structures into the ground.
Electromagnetic vibrations
Characterization of the types of oscillations involves the analysis of the main physical parameters: charge, voltage, current. As an elementary system, which is used to observe electromagnetic waves, is an oscillatory circuit. It is formed when the coil and capacitor are connected in series.
When the circuit is closed, free electromagnetic oscillations occur in it, 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 committed there is no external impact, and only the energy that is stored in the circuit itself is used.
If we consider the resistance of the coil to be zero, and take the oscillation period as T, we can consider one complete oscillation made by the system.
In the absence of external influence, after a certain period of time, attenuation of electromagnetic waves is observed. The cause of 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 the real circuit. A decrease in the charge on the capacitor leads to a decrease in the energy value in comparison with its initial value. Gradually, it will be released in the form of heat on the connecting wires and the coil, the capacitor will completely discharge, and the electromagnetic oscillation will end.
The value of fluctuations in science and technology
Any movements that have a certain degree of repeatability are vibrations. 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, a repetition of charge is observed on the plates of the capacitor. What is the reason for oscillatory movements? The pendulum functions due to the fact that gravity forces it to return to its original position. In the case of a spring model, a similar function is performed by the spring force. Passing the equilibrium position, the load has a certain speed, therefore, by inertia it moves past the average state.
Electric vibrations can be explained by the potential difference existing between the plates of a charged capacitor. Even with its full discharge, the current does not disappear, recharging is carried out.
In modern technology, vibrations are used, which differ significantly in nature, degree of repeatability, nature, as well as the "mechanism" of occurrence.
Mechanical vibrations are performed by strings of musical instruments, sea waves, a pendulum. Chemical vibrations associated with changes in the concentration of reacting substances are taken into account during various interactions.
Electromagnetic vibrations allow you to create various technical devices, for example, telephone, ultrasonic medical devices.
Fluctuations in the brightness of Cepheids are of particular interest in astrophysics, they are studied by scientists from different countries.
Conclusion
All types of vibrations are closely related to a huge number of technical processes and physical phenomena. Their practical importance is great in aircraft construction, ship building, construction of residential complexes, electrical engineering, radio electronics, medicine, and fundamental science. An example of a typical oscillatory process in physiology is the movement of the heart muscle. Mechanical vibrations are found in organic and inorganic chemistry, meteorology, as well as in 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 waves, the results of research by Thomson, Huygens, and Rayleigh. He managed to find practical application of electromagnetic waves, use them to transmit a radio signal over a long distance.
Academician P.N. Lebedev for many years conducted experiments related to obtaining high-frequency electromagnetic waves using alternating electric fields. Thanks to numerous experiments associated with various types of oscillations, scientists were able to find areas of their optimal use in modern science and technology.