Forced oscillations

Electromagnetic oscillations were discovered, to some extent, by chance. Free and forced fluctuations have found wide application in our daily life. Electromagnetic oscillations are used in a variety of technical devices, including in communications. Variable technical currents are also electrical fluctuations. Even light phenomena are electromagnetic oscillations. Let's talk about them in more detail.

Vibrations are understood as processes or movements characterized by a conditioned time repeatability. Such processes are quite widespread. The physical nature of oscillatory processes can be varied. Proceeding from this, electromagnetic, mechanical and other oscillations are distinguished.

Among the various electrical phenomena, free and forced electromagnetic oscillations occupy a special place. Electromagnetic oscillations are understood as oscillations of magnetic and electric fields, accompanied by a periodic change in voltage, current and charge. In order to excite and maintain electromagnetic oscillations, an oscillating circuit is used.

Forced oscillations are such oscillatory processes that are caused by the action of external forces on the system.

Forced oscillations have their own distinctive feature - they are undamped. Their frequency is equal to the frequency of the periodic external action on the given oscillatory system. However, it is necessary to distinguish such oscillatory motions from auto-oscillations. In self-oscillations, the system assumes a mechanism that "delivers" to the system from a certain energy reservoir, in tune with its oscillations, small portions of energy that support its own undamped oscillations. Thus, in self-oscillation, the system "pushes" itself. With forced oscillations, the system takes on impulse from extraneous force.

The frequency of such oscillations coincides with the frequency of the acting external force. At them the amplitude is set not arbitrarily, as with free oscillations, but is established by itself. The amplitude value depends on the ratio of the frequencies of the external force and its own.

Forced oscillations characterize a phenomenon such as electrical resonance. With it, the amplitude of the forced vibrational motions becomes maximum. The amplitude of the oscillations at resonance must be infinitely large. Actually, for it the amplitude of the forced electromagnetic oscillations is finite. With a small resistance in the system, the resistance at resonance will be significant. This makes the amplitude of the vibrational motions at resonance finite. With a greater resistance in the system, the maximum of the amplitude becomes lower at the resonance point.

Alternating current is nothing more than forced electromagnetic oscillations that arise during the 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, vacuum cleaner, refrigerator, TV, etc., used in our homes, work on the basis of the energy of electromagnetic oscillations. Their application is based on the work of electric motors, which drive machines, etc.

In the above examples, an alternating current is used which, in electric energy circuits, is the result of excitation of forced oscillations.

We emphasize that free and forced oscillations differ from one another in that some are performed without external influences due to the energy stored in the circuit, while others are caused by an external effect on the system.