Electromagnetic vibrations discovered, one might say, to some extent by chance. Free and forced vibrations are widely used in our daily lives. Electromagnetic vibrations are used in a variety of technical devices, including communications. Alternating technical currents are also electrical vibrations. Even light phenomena are electromagnetic waves. Let's talk about them in more detail.
Oscillations are understood as processes or movements characterized by conditioned temporal repeatability. Such processes are quite widespread. The physical nature of oscillatory processes can be varied. Based on this, distinguish electromagnetic, mechanical and other vibrations.
Among various electrical phenomena, free and forced electromagnetic oscillations occupy a special place. Under electromagnetic vibrations understand the fluctuations of magnetic and electric fields, accompanied by a periodic change in voltage, current and charge. In order to excite and maintain electromagnetic oscillations, an oscillatory circuit is used.
Forced oscillations - these are oscillatory processes that are caused by the action of external forces on the system.
Forced vibrations have their own distinctive feature - they are undamped. Their frequency is equal to the frequency of periodic external influence on a given oscillatory system. However, it is necessary to distinguish such oscillatory movements from self-oscillations. During self-oscillations in the system, a mechanism is supposed to “deliver” to the system from a specific energy reservoir, in step with its vibrations, insignificant portions of energy that support their own undamped vibrations. Thus, in self-oscillation, the system “pushes” itself. In forced oscillations, the system takes a push from an extraneous force.
The frequency of such oscillations coincides with the frequency of the external force acting. Their amplitude is not set arbitrarily, as in free oscillations, but is set by itself. The amplitude value depends on the ratio of the frequencies of the external force and the eigenvalues.
Forced oscillations are characterized by a phenomenon such as electrical resonance. With it, the amplitude of the forced oscillatory movements becomes maximum. The amplitude of the oscillations at resonance should be infinitely large. In fact, with it, the amplitude of the forced electromagnetic oscillations is finite. With a small resistance in the system, the resistance in resonance will be significant. This makes the amplitude of the vibrational movements in resonance finite. With greater resistance in the system, the maximum amplitude becomes lower at the resonance point.
Alternating current is nothing more than forced electromagnetic oscillations that occur during rotation inside the magnet frame or rotation in the magnetic field of the frame as a result of electromagnetic induction. The alternator is an alternating current source.
Electric lamps, a vacuum cleaner, a refrigerator, a TV, etc., used in our homes, operate on the basis of electromagnetic energy. The operation of electric motors that drive machines, etc., is based on their application.
The listed examples use alternating current, which in electric energy circuits acts as a result of the excitation of forced oscillations.
We emphasize that free and forced oscillations differ from each other in that some occur without external influences due to the energy stored in the circuit, while others are caused by external influences on the system.