STATIC ELECTRICITY

Have you ever felt tingling effect more often during colder seasons, no wires and no power supply and still you get electric shocks? This is nothing but STATIC ELECTRICITY. It is a familiarly encountered phenomenon in which charged particles are transferred from one body to another. For example, if two objects are rubbed together, especially if the objects are insulators and the surrounding air is dry, the objects acquire equal and opposite charges.

The word static means “at rest - not moving”. Static electricity, as opposed to current electricity, is stationary.

Static electricity is the buildup of a temporary electric charge in an object. It refers to an imbalance between the negative and the positive charges on a body. The imbalance in the charge is introduced by physical means and separation between two materials, Rapid heat change etc.

 Static electricity is the electric field which is developed due to the stationary charges. 

METHODS THAT ARE USED FOR PRODUCING STATIC CHARGES:

Electrostatic Induction: It is the process of redistributing the charges on the surface of an object because of the nearby charges or static electric field.

This phenomenon may be observed when an individual dresses in clothes of certain materials. Clothing, especially articles that have been recently dried in a dryer, can become charged with static electricity. When these charged articles are put on, they are attracted to the individual's hair and skin as a result of electrostatic induction.

Triboelectric Effect: If two objects come closer and the charge is transferred between them due to friction is known as the triboelectric effect.

This effect has been observed in the sixth century BCE. 

The discovery of static electricity is usually credited to the Greek philosopher Thales of Miletus. He noted that when the substance amber was rubbed with other objects, it induced movement in nearby particles. Such as particles of dust, would be attracted to it. The word "electricity" is derived from the Greek word which means 'amber'.

The magnitude of triboelectric charging may be strongly influenced by surface contamination of the contacting materials, relative humidity of the atmosphere, and the energy of rubbing.

Static electricity happens more often during winters because the air is drier, and it's easier to build up electrons on the skin's surface. In warmer weather, the moisture in the air helps electrons move off of you more quickly so you don't get such a big static charge.

See if you can create some static electricity by rubbing various materials together!

• A pen rubbed with a piece of cloth will pick up small pieces of paper.
• A television screen collects dust easily.
• Styrofoam and cling film stick to almost everything.
• When you walk across a carpet and then touch a metal doorknob, it results in electric shock to the fingertip.
• When you take off a pullover over a nylon shirt, there is a cracking sound.
• If you roll over in bed, you can sometimes see small sparks between the sheets.
• Most common demonstration of static electric charging is by a person taking off his knit hat or rubbing a balloon on his hair resulting in their hair standing on end by friction. In this case, the balloon gains electrons, becoming negatively charged, while the person's hair loses electrons, becoming positively charged. As the strands of hair are positively charged, they repel each other and attempt to move away from each other. However, as they are attached to the head, standing on end is as far as they can move from one another!
• Gears and belts: V belts, mostly flat power transmission lines, are particularly susceptible to static charge buildup due to the friction between belt and pulley. Rubber conveyor belts employed in material-handling systems do not cause appreciable charge buildup due to their low linear speed.
• Lightning is another most familiar example of static electricity. The accumulation of static electric charge within a thunderstorm cloud is thought to be caused by the triboelectric effect, i.e. friction. As these particles are moved higher and lower by wind and pressure, they rub and bounce against each other, exchanging electrons and gathering charge. As the charges separate and grow, eventually they become strong. After a certain point, the charge imbalance gets too high for the cloud to handle. This means that the charge imbalance has to be neutralized. This is done by opening up a channel of conduction through the air to allow the flow of charges to correct the imbalance. This channel of conduction is known as lightning. 

Once a static charge moves, it is discharged and the static electricity may be neutralized. One way to discharge them is through a circuit and this is exactly what a lightning strike is.

The U.S. scientist and statesman Benjamin Franklin contributed to science with important experiments on electricity. He introduced the concept of positive and negative charge and discovered the electrical nature of lightning through the famous kite-experiment.  He carried out his kite-flying experiments in which he “captured” some thunderstorm electricity in a Leyden jar, that it was verified that thunderstorm electricity and static electricity were one and the same. On this basis, he invented the lightning rod.

CONDITIONS THAT INFLUENCE THE RATE OF GENERATION OF CHARGE:

1. Two dissimilar materials are needed for static build up.
2. Presence of impurities.
3. Interfacial surface between the objects facilitates the migration of electrons between the materials.
4. The higher the speed of separation, the lesser the chance for the electrons to go back to the parent body – and the higher the charge buildup.
5. The speed with which the two surfaces are being rubbed by enhancing the ability of the irregularities on both surfaces to touch, and the heat produced by friction facilitates electron relocation.
6.  Humidity Increases the charge leakage through the air surrounding the charged object, reducing the buildup. The drier the atmosphere, the greater is the charge.
7.  Most organic and polymeric materials have volume resistivity greater than 10⁸ ohms per meter and retain charge for periods of many hours.

APPLICATIONS OF STATIC ELECTRICITY

Although dangerous and necessary to avoid in many situations, Static Electricity has many practical applications. Some examples are:

Ink jet printers and Photocopiers: Ink jet printers and Photocopiers use static electricity to bind the ink to the paper. In this process, the paper is given a positive charge in the areas that are designated to receive the ink. The ink or toner, on the other hand, is negatively charged. The negatively charged ink is attracted to the areas of positive charge on the paper. Finally, heat is applied to dry the ink and a process of scrapping removes any excess ink. This is used in both computer printers and photocopy machines.

Electrostatic Spray painting: Static electricity is used to paint different objects like cars, tools, boats etc. The paint itself is charged and the object to be painted is either given an opposite charge or grounded.  The charged droplets of paint repel one another while being attracted to the body of the car. The result is a much better and more even paint finish on the object. (No area is missed)

Electrostatic Precipitators: A precipitator is a device that uses static charge to remove unwanted particles out of the air. For example, In industrial plants or power generation stations, as smoke and other emissions are produced, an electric charge may be induced in the base of the chimney. As these emissions rise, material holding an opposite charge can be used to collect the particulate which would otherwise become air pollution. Fredrick G. Cottrell developed the first commercially successful electrostatic precipitators. The Cottrell type precipitator is used throughout the world to remove fumes, smoke and small particles from the air.

Fabric Softener Sheets: When clothes dry in a dryer, they rub together, creating static charge. When sheets of fabric softener tumble with the clothes, they act as conductors, allowing electrons to move around the clothes more easily. The molecules of the softener are transferred to the fabrics, making them feel more like one another (so they won’t transfer electrons)

A Van de Graaff generator: A Van de Graaff generator is a device designed to create a static electric charge. 

RISKS OF STATIC ELECTRICITY: The buildup of static electricity is often an undesirable occurrence. Unchecked static electric build up can result in damage to electrical equipment, injuries to people, and even the ignition of sparks causing fires.  

As the charges grow, the charge imbalance has to be neutralized. This is done by opening up a channel of conduction to allow the flow of charges to correct the imbalance. A spark is a discharge of static electricity, which can be clearly seen during lightning.

1. Electric shock due to the flow of current through the body, causing a person everything from an uncomfortable zap to falls, burns, or stopping the heart.
2. Fires or explosions due to the ignition of flammable or explosive mixtures. Fires or explosions due to the ignition of flammable or explosive mixtures. Sparks are responsible for most industrial fires and explosions as a result of static electricity.
3. Damage to electronic equipment and components from electrostatic discharge (ESD). In the microelectronics industry, extremely low-energy discharges, arising from body potentials of only a few tens of volts, can damage microelectronics systems or corrupt computer data. During the handling of some sensitive semiconductor devices, it is imperative that operators work on metallic grounded surfaces and are themselves permanently attached to ground by conducting wrist straps
4. Damage to mechanical components such as bearings due to sparking through the oil films on bearing surfaces. It is vital to analyze the static buildup potential of facilities and establish protective procedures.
5. Production disturbances in the processing of paper, plastics, composites, powder, granules, and liquids. In modern industry, highly insulating synthetic materials, such as plastic powders and insulating liquids are used in large quantities in many applications. Such materials charge up readily, and large quantities of electrical energy may develop with an attendant risk of incendiary discharges. Energetic sparking from charged powder may initiate an explosion of the powder cloud.
6. Similar problems occur when insulating liquids, such as certain fuels, are pumped along pipes, and it is essential that strict grounding procedures are followed during the refueling of aircraft, ships, and other large vehicles.
7. The energy transfer in a spark discharge may reach values up to 10,000 mJ. A value of 0.2 mJ may pose an ignition hazard, although this low spark energy is frequently below the threshold of human auditory and visual perception.

    PREVENTION FROM STATIC ELECTRICITY:

1. Bonding and Grounding to Avoid Sparks: One effective way of preventing sparks is by connecting all objects to a conductor (bonding) and to the earth (grounding). Grounding allows the electric discharge to the ground.
2. Personnel grounding employ specialized flooring and grounding fabrications worn on the wrists or over the shoes.
3. Lightning Conductor: A lightning rod is a metal (conductor) rod that is attached to the roof of a house so that it is the tallest point on the house. A copper wire is run from the rod down into the ground, making a safe path for lightning to travel.
   
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