Electricity between hands

2006/03/01 Kortabitarte Egiguren, Irati - Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Elektronika
• Fisika

(Photo: Archive)

Electrons move by themselves. That is not what we call electric current. However, if we place the electrons between two electric poles, a real current of electrons is generated (electrons are negative electric charges). And that's what we call electric current. In short, the electric current represents the movement or transport of electric charges, which occurs under the influence of the electric field.

Since the transport of electric loads can occur in different types of materials, it will be very important to take into account the characteristics of each material, electrical conductivity, etc.

That is, in some materials it is very easy to do, in others it is not. Metals, for example, transport electric loads more appropriately than any other, but not wood.

In general, electric charges move from a point of greater potential to the point of lower potential, from the positive to the negative pole. Always in that sense. As with gravity, bodies fall from top to bottom and not the other way around. This constant movement is called continuous current and is in nature.

In direct current, the movement of electric charges can be compared to the liquid movement of the pump-driven molecules in a closed hydraulic circuit. The function of the pump is to move the liquid and, in the case of electricity, the voltage provided by the electromotive force is the one that moves the electrical charges of the electric circuit.

The voltage provided by the electromotive force moves the loads of the electrical circuit.

MEC

However, the fact that the positive pole is in Vitoria and the negative in Donostia, for example, makes no sense. Formerly it was consumed where electricity was produced and the direct current was mainly used. However, when the need to transport electricity over long distances arose, the alternating current prevailed to avoid, among other things, the energy losses that occurred during transport.

To obtain alternating current, the electric poles are exchanged cyclically. The exchange of electric poles represents a change in the meaning of the current, and the cyclic exchange gives rise to an electric current that continuously changes meaning. That is, as the name suggests, the alternating current. And that has been invented by man, it is not in nature.

Direct AC current

Both direct and alternating, an electric generator is needed to generate current. The electric generator will create a suitable electric field to maintain the electric current sustainably.

The direct electric current used by humans can have various sources or generators. In batteries, for example, electromotive force and potential difference are obtained through chemical processes. In the dynamos, mechanical energy is transformed into electrical energy. In addition to these two conventional pathways, there is another way of obtaining direct current consisting of rectifying the alternating current. The rectifiers allow to obtain a one-way current, eliminating the opposite direction. Then, by means of electric filters the voltage variation can be softened and the current reached at the end of the process is practically smooth and constant.

Lightning is electric shock that occurs between rain clouds or between cloud and earth.

Archive

Today it is necessary. In fact, alternating current is the current that comes to the homes and the television with which we feed the musical apparatus, the washing machine and the fridge, but then all the internal electronics of these works with direct current. Therefore, among other things, they have a rectifier to convert alternating current into direct current. And other elements like transformers.

Home

Undoubtedly, the invention of the transformer was enormous. Among other things, it faces the energy losses that occurred in transport.

XIX. Developed at the end of the 20th century, it is a fundamental component of power supply networks. It can convert a low intensity and high voltage current into a high intensity and low voltage current (and vice versa), without just losing energy.

The invention of the transformer was enormous.

MEC

This conversion is important. This is because the higher the voltages, the better the performance of the electric power transmission, but the lower voltages are more suitable for generation and use. If there were no transformers, it would be necessary to shorten the distances between generators and users; many homes and industries would need their own power plant and electricity would not be a comfortable type of energy.

In addition to its function in the power supply network, the transformer is an integral component for many objects using electricity. Table lamps, battery chargers and television sets, for example, have transformers that allow to increase or decrease the voltage.

If not, imagine yourself home, for example, with a current of 150 million volts. It would be impossible. The current that reaches homes in Europe is 220 volts and has a frequency of 50 Hz. In the United States, for its part, it reaches between 110 and 120 volts at a frequency of 60 Hz. Therefore, it is advisable to read the instructions of electrical appliances before plugging them into the network.

If you go on vacation abroad and buy an electric appliance, or vice versa, it is very possible that you take your mobile, digital camera or laptop. Often, in these cases, we do not consider that the AC voltage is not the same in all countries, nor is frequency. To address this problem, many of the devices currently have universal adapters.

Health condition

There are still few flashlights that work by driving the crank.

R. Cardboard

We cannot forget, for example, the unpleasant and dangerous consequences of the electric discharge of the voltage of 220 volts in the plug. In general, AC is more dangerous than DC. In fact, the effects of the alternating current on human bodies depend largely on their frequency. The lower the frequency, the more dangerous it is, and between 3 and 4 times more dangerous is the alternating current than the direct current to the same voltage and intensity.

Direct current causes muscle contractions and, in most cases, the affected person moves immediately from the energy source. On the other hand, the impact of the 60Hz alternating current is more violent, leaves the muscles hardened and therefore it is more difficult to free them from the power source. If it persists, serious burns can occur. In general, the higher the voltage and current intensity, the greater the damage, regardless of the type of current.

The use of risks, both direct and alternating current, is extensive. In addition, the latter easily transforms unlike the DC, facilitating its accumulation and reducing energy loss in transport from one to the other. Today no one would imagine a world without electric currents, that is, without electricity.

Friction electricity

Today he has been my co-worker; he has put his hand on his shoulder and zart, karranpa! Yesterday when the car opened. Static electricity is responsible for all these cramps.

We have all had some static electricity experience and some people are more sensitive to these effects than others. Even those who use the car may often notice these effects when touching the sheet with their hand or bringing the key closer to the plate.

We generate static electricity by rubbing a pen on our garments and then we can check that the pen attracts small pieces of paper. The same happens when rubbing the glass with silk or with the wool bar.

How is static electricity generated? For this, we must be aware that matter is formed by atoms, while atoms contain particles with positive and negative charges, protons and electrons, respectively. In general, atoms have as many electrons as protons, so matter is neutral.

In winter we have the driest skin, so we accumulate static electricity.

(Photo: Archive)

Some atoms have great facility to lose their electrons, while others tend to take them. If a material tends to lose electrons, it is said that the material is positively charged. And on the contrary, if the electron tends to win, it is said to be negatively charged.

If you want to generate static electricity, just rub a material prone to electron loss with a material of easy acquisition. Thus, electrons from one pass to another and materials are charged. It is then observed that two materials of the same load repel and attract those who have the opposite.

Among the materials of easy electron loss, people's dry skin ranks first. Animal leather, hair, wool and silk also have the facility of losing electrons. However, rubber and amber attract electrons and more strongly attract nickels and copper, brass and silver, and gold and platinum.

Knowing all this, it is easy to understand why many people have cramps when touching something. The problem is that due to wind and heaters the skin is very dry. The skin, therefore, is charged with a positive sign, especially if wearing polyester clothing, since polyester takes a negative sign. This load is accumulated in the body until it finds static, any metallic object or any other person. Touching it moves the accumulated load and an electric shock occurs. Conclusion: a cramp is felt.

(Photos: MEC and I. Kortabitarte)

In devices that use DC generators, such as batteries or car batteries, polarity always appears and to make connections it is necessary to maintain it. Batteries, for example, if placed backwards, do not work. On the contrary, in domestic electrical appliances supplied with alternating current there is no sign of polarity. If not, why do you think the hair dryer plug comes in equally?