In this paper, we will talk about what iselectromotive force of a current source and what its interrelation with other parameters of an electric circuit. Just note, despite the fact that in everyday life we all successfully use electrical appliances, many laws were derived by experience and taken for an axiom. This is one of the reasons for unnecessarily complicating the definitions. Unfortunately, even electromotive force, this basis of electrical engineering, is illuminated so that a person unfamiliar with electricity can understand something quite difficult. We will explain this question with the help of understandable terms and examples.
Directed motion of charged particles inconductor is called "electric current". As you know, all the objects of our material world are made up of atoms. For simplicity of understanding, we can assume that each atom is represented in the form of a model of the solar system reduced in millions of times: the nucleus is located in the center, and electrons move at different distances from it in circular orbits.
Through some external influence inconductor, which forms a closed loop, creates an electromotive force and an electric current. The action "knocks out" the valence electrons from their orbits in atoms, so free electrons and positively charged ions are formed.
Electromotive force is necessary in order to"Force" the charges to constantly move along the conductor and the elements of the chain in a certain direction. Without it, the current almost instantaneously fades. Understand what is an electromotive force, will allow comparison of electricity with water. The straight pipe section is the conductor. Two of its sides, it goes into the reservoirs. Until the water levels in the reservoirs are equal and there is no slope, the liquid in the pipe is stationary.
Obviously, you can make her move with threeways: create a height difference (slope or the amount of fluid in the reservoirs) or forcefully pump. An important point: if we talk about the difference in height (the potential difference), then the stress is implied. For the EMF, the movement is "forced", since the external forces that have an impact are non-potential.
Any source of electric current has an EMF -the same force that supports the motion of charged particles (in the above analogy makes the water move). It is measured in volts. The name speaks for itself: EMF characterizes the work of external forces applied to the circuit, performing the movement of each unit charge from one pole to the other (between the terminals). It is numerically equal to the ratio of the work of the applied external forces to the value of the charge being transferred.
Indirectly, the need for an EMF source can bederive from the law of conservation of energy and properties of a conductor with current. In a closed circuit, the work of the field with respect to charge transfer is zero. However, the conductor heats up (and the stronger, the greater the current passes through it per unit time). Conclusion: the share of external energy should be present in the circuit. These external forces are a magnetic field in generators, which constantly excites electrons; energy of chemical reactions in batteries.
The electromotive force of induction was for the first timewas discovered experimentally in 1831 by physicist Faraday. He established that an electric current appears in the conductor, which is permeated by lines of tension of a changing magnetic field. The action of the field informs the external electrons in the atoms of the missing energy, as a result of which they break away and begin to move (a current appears). Of course, there is no direct movement of particles (how can we not recall the relativity of the axioms of electrical engineering). Rather, there is an exchange of particles between the nearest atoms.
The developed electromotive force is an internal characteristic of any power source.
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