Physical sense of the equation (consists that the speed of change of energy of a magnetic field on the module is equal to the speed of change of energy of electric field; the sign "minus" specifies that when energy of electric field increases, energy of a magnetic field decreases (and vice versa). Therefore the total energy does not change.
For demonstration of the phenomenon it is possible to use the model collected so that pumps rotated in one party. Serially taking tubes 5 different diameters, show a loading role in a collector chain for strengthening of power.
Similar to the pump and action of a source of current in an electric chain. The pump creates a difference of pressure (pressure) that can be analog of tension. The turbine is similar to the consumer, the pump - to a source of current, a tube with water – to connecting wires, and the crane – to the switch.
Having acquainted pupils with separate elements of an electric chain, it is necessary to collect the elementary electric chain (the consumer — the glow lamp, a current source - the battery of elements, wires and the switch),
It is aware of electricity of the 8th class the picture changes: the model of atom becomes dominating. Here at pupils idea of atom as about the difficult dynamic system consisting of the positive part concentrated in small volume – a kernel and electrons moving concerning a kernel and bearing a negative charge is formed.
About t in t. The electric chain consisting of capacity and resistance can be presented as a limit case of an electric oscillatory contour in which inductance is so small that it can be neglected.
Electromagnetic oscillations in a contour have similarity to free mechanical oscillations, for example with fluctuations of the body fixed on a spring. Similarity belongs not to the nature of sizes which periodically change, and to processes of periodic change of various sizes.
It is known that electromagnetic waves are cross. As light has the electromagnetic nature, light waves are also cross. To understand experiments on polarization of light it is necessary to understand concept plainly of the polarized light and action of a polarizer, and the analyzer.