It’s cold, do you feel the static electricity?

In our daily life, you must have felt static electricity. For example, you feel an electric shock when you shake hands with a friend; your hair "floats" when you comb your hair in the morning; your sweater crackles when you take it off in cold weather... These are all phenomena caused by static electricity.

Let’s take a look at some other interesting knowledge about static electricity.

Image source: soogif

What are static electricity?

As the name suggests, static electricity is electricity in a static state, that is, electric charges gather on the surface of an object and are in a static or non-flowing state.

How is static electricity generated in our daily life? As we all know, most of the substances in our world are composed of molecules, and molecules are composed of different atoms.

Image source: Paixin Creative

Normally, electrons in objects move around atomic nuclei. Because the atomic nuclei in different objects have different abilities to adsorb electrons, electrons will be transferred between objects. Objects that lose electrons become positively charged, and objects that gain electrons become negatively charged.

For example, frictional electrification is the process of repeatedly rubbing electrons from one object to another, accumulating charges and generating static electricity.

Image source: soogif

If there is no conductor path, static electricity will not be transferred from one object to another. Once a path is formed with other objects, static electricity will be transferred in the form of current, resulting in discharge.

For example, when we take off our sweaters in winter, we sometimes hear a "crackling" sound and even see small sparks. This is a typical electrostatic discharge phenomenon. Because the weather is dry, the conductivity of the air decreases, and it is easier for charges to accumulate on the surface of objects. When we take off our sweaters, the sweaters rub against our bodies and accumulate charges. When the charges accumulate to a certain level, they will be transferred through the air and released into the air, completing the discharge and generating sparks.

Image source: soogif

Is static electricity harmful?

First of all, we should know that the generation and accumulation of static electricity is basically unavoidable. A large amount of static electricity accumulation will generate a very high voltage, which may sometimes cause damage to human skin and sometimes affect industrial production.

For example, in the production process of precision instruments and chips, if engineers have static electricity on their bodies, it is possible to break down the chips or capacitors, causing a decrease in product yield; in the production process of medicines, static electricity can easily absorb dust, which may cause the purity of the medicines to fail to meet standards; in flammable and explosive or dust-rich working areas, static electricity can even cause fires and explosions.

Grounding wire丨Source: Theerapong28/dreamstime/IC photo

However, in daily life, people often get "shocked" when they touch other objects (such as door handles, other people, etc.), which causes discomfort. In addition, we use computers for a long time during work and study, and the static electricity generated by the computer screen will absorb a large amount of dust in the air, which will irritate the human eyes and facial skin. Being in this environment for a long time may cause eye discomfort and skin problems.

How to eliminate static electricity?

There are three main ways to eliminate static electricity (accumulated electric charge): 1. Reduce friction; 2. Increase conductivity; 3. Neutralize the accumulated charge.

If you want to reduce friction, the most direct way is to reduce the contact between objects. For example, don't wear fur or synthetic clothes. In addition, part of the working principle of fabric softeners and anti-static sprays is to soften the fabric fibers and reduce friction.

Image source: Paixin Creative

But in real life, we often use the second method - increasing conductivity - to eliminate static electricity.

In factories involved in electronics and chip production, as well as pharmaceutical factories, engineers in production workshops generally wear anti-static clothing, anti-static shoes, and anti-static wristbands to eliminate static electricity. These equipment have good conductivity and can conduct static electricity carried on the surface of the body to the ground as soon as possible, thereby achieving the effect of eliminating static electricity.

Image source: atsawin1002/adobe/IC photo

We can also eliminate static electricity on our bodies through a series of small "tricks" based on the same principles.

For example, using a humidifier in the room in winter to increase the humidity and conductivity of the air can effectively alleviate the accumulation of static electricity (the same is true for the other part of the anti-static spray); using body lotion to ensure the moisture of the skin and increase the conductivity of the skin can also effectively reduce static electricity on the body; before pushing open a metal door in winter, you can first put your entire palm against the wall, or hold the key in your entire hand and then touch the metal door, both of which can effectively eliminate static electricity.

Image source: Chongqing Science and Technology Museum

The third method of eliminating static electricity through charge neutralization is generally not used in life.

How to use static electricity?

Static electricity has more or less brought some impact to our lives, but as long as we fully understand the nature of static electricity, static electricity can also serve mankind.

The COVID-19 pandemic that has ravaged the world from last year to this year has made people all over the world aware of the importance of wearing masks to prevent the spread of the epidemic. The reason why masks can isolate viruses is that the core part is the electrostatic meltblown cloth in the middle layer of the mask (usually blue). Through the electret process, the meltblown cloth is given electret static electricity. By using the characteristic of static electricity that can absorb fine dust, virus-carrying particles and dust are adsorbed on the surface of the meltblown cloth to achieve the purpose of filtering viruses.

This is why masks need to be stored in a moisture-proof manner and need to be replaced in time after a period of use, because the protective effect will be greatly reduced after the static electricity carried by the meltblown cloth in the middle of the mask is lost.

In addition, electrostatic copying, electrostatic printing, electrostatic spraying, electrostatic dust removal and other technologies have also been widely used in industrial production.

my country has carried out a series of research on static electricity since the 1960s, and established the Electrostatic Professional Committee of the Chinese Physical Society in 1981. By studying the characteristics and hazards of static electricity, electrostatics, as a specialized discipline, has been widely used in the electronics industry, petroleum industry, textile industry, weapons industry, aerospace and other fields.

About the Author

Hu Anbang, majoring in nuclear engineering.

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Editor: Ren Yalin

The article is owned by Chongqing Science and Technology Museum. Please indicate the source when reprinting it.

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