Stationary Electric Charge
Let’s begin by defining what static electricity actually is: It is a stationary electric charge, typically produced by friction, which causes sparks or crackling. It always occurs between two objects. One of the objects is supposed to be positively or negatively charged while the other is in a neutral state. When these two objects interact the charges on them get displaced within the objects or on their surfaces. We call this interaction static electricity.
All matter is composed of atoms, which are further made up of subatomic particles – electrons that are negatively charged, protons with a positive charge, and neutrons which are neutral. An atom naturally tries to exist in a neutral state by balancing out the number of electrons and protons so that it can attain stability. Hence, all matter around us is electrically neutral. The electrons are in a continuous circuit around the nucleus due to their attraction towards the positively charged nucleus. These electrons, however, have extremely low mass, which is why friction can cause the loosely bound electrons to leave the atom and attach to other surfaces. The atom which loses an electron becomes positively charged and the one that gains an electron becomes negatively charged. These charged atoms are called ions and the phenomenon is called charge imbalance. The ions try to attain a state of “equilibrium”. This state of equilibrium is achieved when a negatively charged ion gives its extra electrons to a positively charged ion, this transfer of electrons is called electrostatic discharge or ESD. This discharge is what we recognize as a “zap” or a “spark” in our everyday lives.
The imbalance of charges takes place due to multiple reasons. These reasons can be natural or self-induced. One of the most common demonstrations of static electricity is rubbing a balloon on your head, and making your hair stand up. The rubbing will displace the balloon’s neutral state and create dipoles, resulting in the hair standing up straight on your head when the balloon is brought in contact with them.
Figure: Depicting static electricity phenomenon of inducing charges on the surface of the balloon and the hair.
Another way static electricity can be induced in a material is by using heat. Heating also causes an imbalance of the charges. So when you use a hair straightener or a blow dryer you get all your hairs charged up and they start sticking out, on top of your head.
Our body has its own electric charges, and when these charges get distorted we experience a shock. Many of us have experienced this shock, sometimes when we bang our elbows with someone we can experience it. The intensity of the shock varies for different people. A human body has 10 mA (milliamperes) of internal current. The same thing happens with our bodies. The electrons move to different surfaces, leaving behind a positive charge and when we come in contact with an object which has a negative charge, we get the feeling of a shock. The shock is referred to as electrostatic discharge or static discharge. Objects like wool, hair, glass, and human skin tend to experience more electrostatic charges than other materials.
A common example of static electricity is when you walk on a carpet in socks. This shuffling creates an imbalance of charges, your body gains electrons and becomes negatively charged and these electrons are discharged when you come in contact with another person or some object such as a doorknob. The rapid flow of electrons from your body to the other object gives a sensation quite similar to that of an electric shock. However, the intensity of an electrostatic shock is much less in comparison to an electric shock. In some cases, people observe sparks as well. Sparking occurs when the electric potential exceeds by a certain limit, depending on the object.
The lighting we see in the sky is also a phenomenon of static electricity. There exists friction between the clouds and the air. This friction acts as an ionizing force between the two entities, displacing positive and negative charges in its path. Also, the elements in the air lose their neutral states and acquire negative or positive charges, this charge imbalance creates a chain to the surface of the Earth. So when the current is conducted through that chain of variable charges, we see the flashes of lightning.
Static electricity is generated in areas of low humidity. People living in cold and dry climates tend to experience electrostatic discharges a lot more than others. Because a lack of moisture creates the perfect environment for the charges to move about without any air resistance. Water droplets present in the humid air play a major role in dissipating the ions, preventing static shocks.
The important question is why should we go to such lengths to prevent a tiny shock?
It doesn’t cause any real harm. Well, it does. The frequent zapping isn’t a welcoming sight; it undeniably places one under quite a strain. And why shouldn’t one remedy it?
Moreover, our nervous system, which comprises of the brain, spinal cord, and nerves is extremely sensitive to shocks. A single jolt can cause mild or severe damage. This damage results in muscular problems nerve damage and possibly paralysis in extreme cases. Sometimes, it can’t even be treated which results in permanent injuries.
In an industrial setting, the static discharges which result in sparks are a source of ignition. A single spark can generate up to 3,000 volts of electricity. The current is low but it can be extremely dangerous to applications that deal with flammable materials. There have been several explosive accidents attributed to static electricity. A single spark from one’s rubber-soled shoe can be responsible for causing a huge catastrophe. An example of such an industrial incident, which took place in Oklahoma, in 2003 was when a storage tank exploded and the culprit was traced out to be an electrostatic spark.
Many other similar incidents have taken place all around the globe in factories that deal with flammable and combustible goods.
Another common problem that industries face these days due to static electricity is slow manufacturing and damages to their final products. The movement and friction from the manufacturing line can ionize a product. The electrically charged products can wreak havoc in the manufacturing line. The ionized product will now repel or attract other objects as it moves along the manufacturing process. This can cause serious problems on the production floor, from slowing down the productivity to the assembly and final packaging of the product. A single spark can cause permanent changes to an object’s functioning. For instance, in a semiconductor device, a single zap can change its circuit’s intended function and lower the yields and result in loss of revenue.
Another issue regarding static is the attraction of unwanted particles of dust, dirt, and microorganisms. Many of us have noticed a fine layer of dust sitting on our televisions. This dust accumulation is due to static. The charge generated by the television attracts the dust particles to cling to its surface. A similar thing takes place in industries, the ionized products attract electrons, which in turn carry dirt and microorganism with them. Imagine all this taking place in the food industry, the food prepared there would be contaminated and unsafe for consumption, resulting in major health risks and money loss.
Electrostatic discharges and sparks can very easily be prevented by taking simple measures. We can use humidifiers to create moisture in a dry environment. We can use anti-static sprays, and anti-static substances to coat materials that are more prone to static. Fabric softeners and dry sheets are examples of the anti-static substance that remove and hinder static charge accumulation. Static shocks can be prevented by wearing more cotton fabrics, instead of wool and nylon. Avoiding rubber-soled shoes is also a major contributor to preventing sparks caused by static electricity.
A brilliant way to prevent static discharges is by using anti-static mats. These mats act as resistors between two charged surfaces since current tends to flow through paths of low resistance. The circuit of electrical conduction will be incomplete and the body will stay safe from the shock. All of this will be due to the zone of high resistance created by the mat.
As we all have heard, it better to be safe than sorry, a small investment in anti-static products can be of great value.