The emergence of E. D. with. induction in a straight conductor, moving in a magnetic field, it was explained by the action of the Lorentz force on the moving charge carriers. However, to explain in this way the appearance of e. d. with. induction in the secondary circuit when it is stationary relative to the primary circuit (it was impossible, since there is no magnetic field on resting charges.

Remember, resting on the charge acts the electric field. It creates an induction current in the secondary circuit? If so, where this electric field is taken? It can be explained, that variable magnetic field can create electric field, that already excites in a confined conductor of the induction current.

This explanation of the phenomenon of electromagnetic induction was first given Dr.. Maxwell. Developing this idea, he created the theory of electromagnetic field, which has been confirmed by many experiments. According to Maxwell's theory in space, which changes the magnetic field, be sure to have an electric field with closed lines of tension, regardless of the presence of the substance.

In figure. 23.8 straight line represent changing magnetic field with induction In, increasing (and) and decreasing (b), and closed ways — arising electric field, the tension which E. If in this space will be the conductor, then it will arise an induction current. For example, when withdrawing the magnet from the coil in figure. 23.3, g an electric field, depicted in figure. 23.8, b, which creates the current in the solenoid. (Explain, how does the current in other cases, shown in figure. 23.3.)

In figure. 23.8 see, the lines of electric and magnetic fields are in mutually perpendicular planes. Studies have shown, the intensity vector (induction) the magnetic field in each point of space is perpendicular to the intensity vector of the electric field created by it. That is why most e. d. with. induction in a straight conductor arises, when it moves perpendicular to the lines of the magnetic field.