from PxHere

Xerox machines, laser printers, and powder coating are just a few of the many uses of Coulomb's Law that can be seen in today's world.
Using a rod of amber and rubbing it on your cat's fur can attract feathers and other light objects, according to the ancient peoples of the Mediterranean Sea. Magnetite, for example, was well-known to the ancient Greeks for its magnetic properties.

A distinction was made between magnetism and static electricity by the English scientist William Gilbert in 1600, and he dubbed the static electricity force electricus after the Greek word for "amber." It wasn't until 1767 that the English scientist Joseph Priestley made the formal proposal that the electrical force between two charged objects diminishes with the square of the distance between them. Priestley is most recognized for being the discoverer of the element oxygen as well as the inventor of carbonated water. So, the next time you take a sip of Coca-Cola, remember Joseph Priestley.

In 1785, the French physicist Charles-Augustin de Coulomb published three papers on electricity and magnetism, in which he explained the electrostatic force in greater detail than anybody else. According to Coulomb's Law,

1. Like charges repel each other and unlike charges attract one another.
2. The attraction or repulsion between the two charges occurs along a line drawn between them.
3. In addition to being proportional to the product of their respective charges, force magnitude is also related to the square of their distance from one another
   (see Figure below)

F∝ q1q2
Or, F∝1/r2
F = k q1q2/ r2

The charges' signed magnitudes are q1 and q2, and the distance between them is measured by the scalar r. The newton, the coulomb, and the meter are all units of force, charge, and distance, respectively.

The inverse-square behaviour of the electrostatic force, as described by Isaac Newton's law of universal gravitation, is surprising identical to that of gravity.

_{Haloid Becomes Xerox}
When Chester Carlson was a patent attorney working at the US Patent Office in New York City in 1938, he was a pioneer in the field of intellectual property law. Carlson's arthritic hands made it difficult for him to copy large numbers of documents by hand. He built the first photocopy machine by tinkering around in his kitchen at night.
At least 20 companies, including IBM and General Electric, rejected Carlson's copy machine invention during the period from 1939 to 1944. In 1947, a small New York photographic paper manufacturer, the Haloid Corporation, was granted permission to use Carlson's invention in the development of the copy machine.

The Haloid Corporation was renamed the Xerox Corporation after consulting a professor of classical languages who coined the term "xerography" from the Greek words xeros for dry and graphos for writing.

Duplicates are created by the electrostatic process. In this case, the drum is made of aluminum coated with selenium, which has an unusual property: when in darkness, it acts as an insulator but when exposed to light, it acts as a conductor

_{Copier inside toner printer}
Source

The process of xerography begins with the introduction of negative charge under a thin layer of positively charged selenium during the initial stage of xerographic development.

As a result, the drum surface is exposed to the picture to be reproduced, and where the image is light, the positive charge is neutralized, and where the image is dark, the positive charge remains in place. The image has been transferred to the drum at this point.
This is followed by the application of a black powder, termed toner, that has been charged with a negative charge.

The toner is pulled from the drum by a blank piece of paper that has a higher positive charge than the drum. Finally, the paper and toner are heated rollers that melt and permanently adhere the toner to the paper.

It is the same process that is used in laser printers to create positive-charged images, and the resInkjete process is the same as in xerography. Laser printers can produce high-quality images because laser light can be precisely controlled.

Inkjet printers also use the electrostatic method, which involves spraying tiny ink droplets via a nozzle before applying an electric charge to each one. With the help of charged plate pairs, the droplets are guided onto paper, where they create letters and images. Colour inkjet printers use black, cyan, magenta, and yellow inkjets to produce colour images.

Powder Coating, It's Not Just For Motorcycles

Electrostatic painting or coating commonly referred to as "powder coating," is another application of the electrostatic process. The sprayer and the object to be coated are both charged with high voltage electrostatic currents during the operation.

Electrostatic charge accelerates a covering of powdered particles or atomized liquid toward the workpiece. The ionic bond between the coating and the item results in a homogenous coating with excellent adhesion.

Colour mixing and bleeding can be achieved by applying multiple powder colours before curing them all at once. Because of this, powder coating is a favourite among motorcycle fans throughout the world.

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Reference

What Are the Applications of Coulomb's Law?
Coulomb’s Law Examples in Daily Life
Coulomb’s Law

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