Unveiling the mystery of static electricity: Research reveals how friction generates static electricity

Scientists have explained for the first time how friction between surfaces can generate an electric current.

Researchers Northwestern University have solved a long-standing mystery: why objects rubbing against each other can produce static electricity. They discovered that different forces at the front and back of a sliding cause different charges to accumulate, resulting in an electric current. This insight, which dates back to the ancient observations of the Milesian Thales, has significant implications, preventing industrial accidents to enhancing drug dosages.

Understanding static electricity: a breakthrough discovery

Anyone who has ever pet a cat or shuffled their feet across a carpet knows that rubbing against each other can produce static electricity. But for more than two thousand years, researchers have been unable to find an explanation for this phenomenon.

Now, scientists Northwestern University have finally discovered the mechanism behind it.

The researchers found that when an object slides, the front and back parts of the object experience different forces. This difference forces causes different charges to accumulate at the front and back of the object. The difference in charges can produce an electric current, resulting in a mild electric shock.

Expl an ancient phenomenon

Lawrence Marks, a professor at Northwestern University who led the study, said: "For the first time, we have been able to explain a that no one else has been able to explain: why friction is important. People have tried, but they could not explain the experimental results without making unreasonable or implausible. Now we can, and the answer is surprisingly simple. The front and back of a sliding object have different deformations, which produce different charges, and this will a current."

As an expert in surface structure, Marks is a professor emeritus of materials science and engineering at Northwestern's McCormick School of Engineering. Karl Olson a graduate student in Marks's research group, is the first author of the paper.

The historical background of static research

In 600 BC, the Greek Thales of Miletus first reported static electricity caused by friction. After rubbing amber with fur, he noticed that the fur would attract dust.

Marks said: " then, it has been clear that friction can cause static electricity in all insulators, not just fur. However, this is more or less where the scientific consensus endsShear: the secret behind static electricity

Marks and his team began to unravel this mystery in 2019. In a study published in Physical Review Letters they reported that rubbing two materials together can cause the tiny bumps on the surface of the materials to bend. The researchers found that these bent, deformed bumps can produce voltage.

"In 2019, we had the seed of what was about to happen. However, like all seeds, it needed time to grow. Now it has blossomed. We have developed a new model for calculating current. The values of the current in different situations agree well with the experimental results."

A concept calledelastic shear" is at the heart of the new model. Elastic shear occurs when a material resists the sliding force. If a person pushes a plate across a table the plate will slide. Once the person stops pushing it, the plate stops moving. This additional friction caused by the resistance to sliding can cause charges to move.

"iding and shear are closely connected," Marks said.

The static electricity