7 junio, 2024

Static electricity: concept, how it is produced, examples

We explain what static electricity is, how it is produced, the effects on the body and we give several examples.

What is static electricity?

The static electricity It is a natural phenomenon that arises when a material has lost or gained electrons. It happens frequently in insulators, but metals can also hold electrical charge on occasion.

It is a temporary situation, since the charge imbalance is restored shortly, when the charged material gives up the excess of electrons or takes electrons to recover neutrality.

The phenomenon of static electricity is closely linked to the structure of matter. The atoms of any substance, whether gas, liquid, or solid, consist of a nucleus of positively charged protons and uncharged neutrons, orbited by negatively charged electrons.

Generally, materials are in a neutral state, but occasionally, thanks to contact with other materials, they can lose or gain electrons, causing them to be left with a net positive or negative charge.

Materials that easily lose electrons become positively charged, such as hair, wool, and glass, and those that tend to gain them become negatively charged, such as paper and plastic balloons. These charges do not circulate, but remain in certain areas of the material, hence they are called static.

Static electrical charges are governed by a fundamental principle: charges of opposite signs attract and charges of the same sign repel each other.

So, if a charged material comes into contact with another that has a charge of the opposite sign, a temporary attraction occurs, or a spark appears, as a consequence of the transfer of electrons, which tends to restore the neutrality of the materials.

How is static electricity produced?

Friction or rubbing between two materials of a different nature is often the cause of static electricity, as will be seen later in the examples section. In this way, some materials will give up electrons and others will gain them, thus generating a net static charge on each one.

Apart from friction there are other ways to produce static electricity.

Contact and induction electrification

An object can become electrified by direct contact with another charged object. And if there is no direct contact, but an approach, still objects can be charged by induction.

Electrical induction is observed in metals, as they have free electrons that move throughout the material. If a positively charged object is brought close to a metallic object in a neutral state, the electrons in the metal will accumulate in the nearest part, and the effect will be attractive.

But if a negatively charged object approaches the neutral metal, the effect will also be attractive, because the metal’s electrons will be concentrated in the farthest part, leaving the nearby region with a negative charge deficit, that is, a positive charge.

ANDstatic electricity in the body and its effects

The body can act as a capacitor and accumulate static electricity. When enough charges have accumulated, contact with the water contained in the air, which is a good insulator, produces the discharge, as long as the humidity percentage is adequate.

But if this percentage is low and the air is very dry, the charges continue to accumulate without the person noticing, until it occurs to them to touch a metallic object such as a doorknob, car door or even another person. The discharge produces an unpleasant tickling sensation that can cause startle.

Factors Affecting Charge Accumulation

People accumulate static charge thanks to factors such as:

The way of walking or moving and the type of pavement Type of shoe sole Making contact with bodies that are easy to charge electrically or electric fields of a certain intensity. The degree of humidity of the skin The percentage of environmental humidity Use of clothing made of synthetic fibers, as well as rubber gloves and footwear.

risks

Apart from the unpleasant sensation caused by the discharge, the risk is not excessive on a daily basis, although people with pacemakers must be vigilant.

However, for those who work with easily ignitable substances, special precautions must be taken to avoid explosions and accidental fires.

There is also the risk of tripping, falling or making a mistake when operating machinery, after the operator receives the discharge.

On the other hand, static electricity causes dust to accumulate that clogs ducts and filters, causing numerous inconveniences in the operation of machinery and malfunctions in electrical and electronic parts.

Examples of static electricity

Sheets

Sheets of paper passing through the printer mechanism sometimes get stuck together. It is due to the friction between the sheets and the rollers of the printers, when by rubbing, electrons from the material with which the rollers are made pass to the paper and vice versa.

clothes in the dryer

If freshly washed clothes are put to dry in the electric dryer without fabric softener, shirts and socks tend to stick together. When taking them off, a few clicks are heard and again, the culprit is friction, which separates electrons from some fabrics and makes them pass to others.

Amber

By rubbing a piece of amber with a woolen cloth, it is capable of attracting bits of paper, just like a comb that has been run through your hair.

automobiles

Cars can accumulate electrical charge. We have already seen that insulators charge and retain charge, but metals can also do so if they are insulated from the ground, and car tires are made of rubber. A person touching the charged sheet metal continues the circuit to ground and feels a brief electrical discharge.

The photocopier

Copier paper is statically charged with a pattern of charges that duplicates the image to be copied. The carbon used in the ink is oppositely charged, so it adheres to the pattern on the paper to form the image.

Laser printer

The image pattern is formed on a light-sensitive drum in the printer, which is illuminated with a laser beam.

The drum rotates and the laser beam illuminates certain areas, in accordance with the pattern of the image, and in doing so, gives them a negative charge. For its part, the toner is a powder of graphite with an electro-positive trend, which adheres to the pattern created by the laser on the drum, after which the powder is transferred to the paper to form the image.

Spray paint

In the spray gun of a paint gun, each drop of paint becomes positively charged so that they repel each other, making it easier for them to spread over the surface to be painted and spread more evenly. If the surface to be painted is metallic, then it is negatively charged so that the paint droplets are attracted to the surface.

Clouds

In the clouds there are drops of water and dust particles, which are constantly removed by the wind. The constant collisions cause the electrical charges to separate, occupying different regions of the cloud, but the same air friction then prevents the different charges from attracting each other.

When a critical charge is finally reached, electrical discharge occurs between the clouds and the Earth, which by the way is also conductive. From the Earth to the clouds, channels are also opened through which the charges circulate, which interact with the air molecules at high temperatures, producing lightning. The shock wave generated is what produces the thunder boom.

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