Giving current in an external chain, the accumulator is discharged, processes proceed in it upside-down. At the end of discharge both plates appear the covered identical layers of sulfate of lead, and E.D.S. of the accumulator falls down to zero.
At rather big intensity of a field (about 3 MV/m) between electrodes there is an electric spark having an appearance of brightly shining twisting channel connecting both electrodes. Gas near a spark heats up to high temperature and suddenly extends, why there are sound waves, and we hear a characteristic crash.
James Franck and Gustav Gerz's experiences. The studied gas with a pressure about 0,1 - 0,01 mm hg is entered into a glass tube which at first is pumped out to high vacuum (for removal of others of gas. The tube has the heated cathode, a grid and a collector of ions. On a grid moves positive (rather potential which can be changed by means of a divider of tension and to measure the cathode by the voltmeter. On the collector of ions negative potential, on 0,5 - 1,0 In bigger, than cathode potential is imposed. This small potential difference is removed from tension divider which positive end is connected to the cathode.
After cancellation of the ionizer the number of ions in gas decreases eventually and the end of the ends ions disappear at all. Disappearance of ions is explained by that ions and electrons participate in the thermal movement and therefore collide with each other. At collision of a positive ion and electron they reunite in neutral atom. In the same way at collision of positive and negative ions the negative ion can give the excess electron to a positive ion and both of them will turn into neutral atoms. It is process of mutual ionization of ions is called as a recombination of ions.
The method of Franc and Hertz is not the only method of measurement of energy of ionization. It can be defined also from research of line spectra of a luminescence of the rarefied gases and vapors, and with quite big accuracy. The values of energy of ionization found on ranges well coincide with its values determined by method of electronic blows.
It is convenient to observe the smoldering category with the lowered gas pressure. If to put constant tension in some honeycombs of amperes to the electrodes which are sealed in a glass tube 30-50 cm long and then gradually to pump out air from a tube, the following phenomenon is observed: with an atmospheric pressure the enclosed tension is not enough for breakdown of gas and the tube remains dark. At reduction of pressure of gas at some moment in a tube there is a category having an appearance of the shining cord. At further reduction of pressure this cord extends and fills all section of a tube.
The free electron 1 at impact with a neutral molecule splits it on an electron 2 and a free positive ion. Electrons 1 and 2 at further impact with neutral molecules again splits them on electrons 3 and 4 and free positive ions, etc.
The distance the cathode grid in such tubes is done considerably smaller, than distance a grid collector, and select gas pressure so that the average length of free run of electrons in gas was more than a distance between a grid and the cathode. Therefore the electrons which are let out by the cathode move in space the cathode grid practically without impacts and if the potential difference (expressed in volts), between a grid and the cathode is equal, each electron gains the kinetic energy (expressed in electron-volt). The electrons accelerated by a grid test then impacts with atoms of gas in space between a grid and a collector.
The crown category arises as at negative potential on a wire (negative crowns, and at positive (positive crowns, and also at an alternating voltage between a wire and the cylinder. At increase in tension between a wire and the cylinder also current grows in the crown category. Thus thickness of the shining crown layer increases.
Let's consider this phenomenon on the example of a lamp. In a lamp the metal conductor on it is sealed electric current is passed, the conductor heats up and from it electrons take off. There is also the return process – electrons come back to the conductor – process of a recombination.
Gases do not install electrical equipment in natural state. If to place in dry atmospheric air well isolated charged body, for example the charged electrometer with good isolation, the electrometer charge long time practically remains invariable.