In 1870, the English physicist John Tyndall demonstrated an interesting experience in the propagation of light through a stream of water. Light from a carbon arc is introduced through a lens into a water stream. Due to the multiple internal reflections of the rays at the boundary of two media - water and air - the jet glowed along its entire length. It was the first light guide - liquid.

After 35 years, another scientist, Robert Wood, suggested that "light without large losses can be transmitted from one point to another, using the internal reflection from the walls of a glass stick." So the idea of ​​a solid transparent light guide came up.

50 years passed from the emergence of this idea to its realization, until in the late 1950s, two-layer glass fibers with different refractive indices were obtained: large in the inner and smaller in the outer layer. As in the Tyndall experiments, due to multiple reflections at the interface of two media, a light beam propagated along the fiber - from the transmitting end to the receiving one ...

An article on the use of a device that allows you to competently distribute the power supplied by electric networks.

The end of the nineties. All free capacities in distribution networks are almost selected. The prices for obtaining permission to connect capacity are galloping at an awful rate. But in order to give, the population needs power, distribution networks need to reconstruct and build a huge number of networks and distribution substations.

Financing for the modernization program is practically not allocated. The consumer has to shoulder the problems of distribution networks. According to the technical specifications issued by the same networks, reconstruct or build high-voltage lines in order to bring the point of connection of their capacities closer to the place of their own construction. To buy equipment or finance the reconstruction of distribution substations. And all this in order to get to the house or cottage not 3 kW, but at least 10 kW. So, we will talk about this category of consumers. I will give an interesting example of the relationship of this category of consumers ...

It is hardly worthwhile to talk in detail about the enormous damage caused by metal corrosion. This is common knowledge. Recall only one (also well-known) figure: approximately a tenth of the metal mined per year is spent to cover the irrevocable corrosion losses.

Summarizing the losses caused by corrosion damage, it is impossible to discount the premature failure of machines, parts, metal structures, and the costs of all kinds of protective measures: the development, production and application of corrosion inhibitors, galvanic and paint coatings.

The last of the listed methods of corrosion protection is the most massive. Varnishes and paints protect cars and pipelines, bridges and tanks, ships and building structures from the damaging effects of the environment. But sooner or later, red traces of rust still appear on the metal surface ...

One of the main drawbacks of squirrel-cage induction motors is their high inrush currents. And if theoretically the methods for reducing them have been well developed for quite some time, then almost all of these developments (using starting resistors and reactors, switching from star to triangle, using thyristor voltage regulators, etc.) were used very rarely.

Everything has changed dramatically in our time, becauseThanks to the progress of power electronics and microprocessor technology, compact, convenient and efficient soft-start devices for electric motors (soft starters) have appeared on the market.

Soft starters of induction motors are devices that significantly increase the life of electric motors and actuators operating on the shaft of this motor ...

The doctrine of electromagnetism has been criticized for a long time, speaking about it: incomprehensible, complex, contradictory.

Indeed, there are about a hundred paradoxes in it. However, their theoretical analysis, so to speak, theorization, refinement, despite the usefulness of such a lesson, sometimes still smacks of something cabinet, speculative. In such cases, one involuntarily wants to ask: is there anything new in practice, in experiments, that would even astonish the most experienced theorists?

I must say that unusual experiments, nevertheless explainable within the framework of the existing doctrine, can be counted with a dozen. Among them there are those who finally open the way to a new electrodynamics - clear, simple and logical, devoid of paradoxes.

Let's talk about both. Extremely spectacular look "motors" in which between the electrodes, where the high voltage is connected, a variety of objects rotate frantically. One such wheel was built by Franklin. The principle of its operation is very simple: charges flowing from the electrodes onto the rotor are repelled by the Coulomb forces ...

Electrical wiring in the house: installation features

Not so long ago, in Soviet times, wiring was routed around the rooms strictly along the walls, switches and sockets were installed in uncomfortable places for use, often making room furniture problematic. Today, the usual “wall” installation is being replaced by floor, or more precisely, underground.

Laying the electric network under the floors is much more convenient from the point of view of economy, because the wires are mounted directly, along the shortest path, which can reduce the consumption of materials sometimes up to 40% (!). In addition, hidden in the floor wiring implies absolutely free placement of furniture. Outlets will not loom in the middle of the wall: they can be led directly to the equipment, for example, hidden under a computer table, even if this table is in the middle of the room ...

So far, electric cars are not very relevant, but the future lies with them. After all, they use an inexhaustible resource and are absolutely environmentally friendly and cheap.

When pronouncing the word - an electric car, it makes us smile and only a car from a science fiction film comes to mind. Although in the world, they are actively inventing and are already driving them.

Russia has long been accustomed to driving large and powerful SUVs, especially on such off-road conditions. Everything is changing in the world, the global financial crisis shows instability and sharp jumps in oil prices. They make us look further into the future ...

According to existing Russian standards, consumers are supplied with single-phase power supply with variable characteristics, that is, with alternating current.

The rated voltage is 220 volts with a frequency of 50 Hz. But there are such cases that sharply pop up in rural areas and in summer cottages, when we need to connect a three-phase electric device to work.

An example of such a device is a power-saw bench, powerful pumps, electric tractors, various types of threshers and meat grinders, concrete mixers. So where to get these two missing phases? In fact, there is nothing complicated in this and will be on the shoulder of anyone who is more or less versed in electrical engineering and energy.

Usually in such cases, we are advised to purchase a portable generator. But you can do without it, or at least use a cheaper option - a three-phase asynchronous squirrel-cage electric motor ...