A New Study from Northwestern University Unveils the Mechanism Behind Static Electricity Generation Through Friction
Anyone who has ever petted a cat or walked barefoot on a carpet knows that rubbing objects together generates static electricity. However, a satisfactory explanation for this phenomenon has puzzled scientists for over 2,000 years.
The study published in the journal Nano Letters demonstrates that when an object slides, its front and back experience different forces. This difference in force causes varying electric charges to accumulate at the front and back of the object. Consequently, the charge disparity generates a current, leading to a small electric shock.
Petting a cat creates static electricity – (Illustrative image: mccormick.northwestern.edu).
Professor Laurence Marks, who led the research, emphasized: “For the first time, we can explain a mystery that no one has been able to solve before: why friction plays such a crucial role.”
“People have tried, but they could not explain experimental results without making unfounded or unjustifiable assumptions. Now we have succeeded, and the answer is surprisingly simple. It is enough to have different deformations, leading to different electric charges, at the front and back of a sliding object to generate a current.”
Professor Marks revealed that the research team developed a new model to calculate the electric current, where the concept of “elastic shear” plays a significant role.
“Elastic shear” occurs when a material resists sliding forces. For instance, if someone pushes a plate on a table, the plate resists sliding. Once the person stops pushing, the plate ceases to move. This new frictional force, due to the plate resisting sliding, causes the electric charges to shift.
“Sliding and shear are closely related”, Marks explained.
He also emphasized that static electricity impacts life in both simple and profound ways. “It affects how coffee beans are ground and their flavor. The Earth might not have become a planet without the crucial step in the process of accreting the particles that form planets, which occurs due to the static electricity generated by colliding particles,” he stated.
The phenomenon of static electricity due to friction was first recorded by the Greek philosopher Thales of Miletus around 600 BC. After rubbing amber with fur, he noticed that the fur attracted dust.
Although static electricity can lead to humorous incidents, such as hair standing on end after sliding down a playground slide, this phenomenon can also result in serious issues. For example, sparks from static electricity can cause fires or even explosions in industrial settings.
Static electricity can also interfere with consistent dosing for powdered pharmaceuticals.
