Triboelectric effect

Phenomenon where certain materials become electrically charged after coming into contact with a different material

The triboelectric effect is a type of contact electrification in which certain materials become electrically charged after they are separated from a different material with which they were in contact. This phenomenon is commonly experienced in everyday life, such as when a person walks across a carpet and then touches a metal doorknob, resulting in a static shock.

Mechanism

The triboelectric effect occurs when two materials are brought into contact and then separated. During contact, electrons may transfer from one material to the other, depending on their relative positions in the triboelectric series. The material that loses electrons becomes positively charged, while the material that gains electrons becomes negatively charged.

The amount of charge transferred depends on several factors, including the nature of the materials, the surface roughness, and the environmental conditions such as humidity. The presence of asperities or microscopic surface roughness can enhance the effect by increasing the contact area.

Triboelectric Series

The triboelectric series is a list that ranks materials according to their tendency to gain or lose electrons. Materials at the top of the series, such as glass, tend to lose electrons and become positively charged, while materials at the bottom, such as rubber, tend to gain electrons and become negatively charged.

Applications

The triboelectric effect has several practical applications. It is used in triboelectric nanogenerators (TENGs) to convert mechanical energy into electrical energy. These devices can harvest energy from various sources, such as human motion or environmental vibrations.

The effect is also utilized in electrostatic precipitators to remove particles from exhaust gases in industrial processes. Additionally, it plays a role in the operation of xerography, a dry photocopying technique.

Hazards

The triboelectric effect can pose hazards in certain situations. For example, static electricity generated by the effect can ignite flammable gases or dust, leading to explosions. In the electronics industry, static discharge can damage sensitive components, necessitating the use of antistatic measures.

Related pages

• Static electricity
• Electrostatic discharge
• Electrostatics
• Contact electrification

References

• Jones, T. B. (2001). Electromechanics of Particles. Cambridge University Press.
• Harper, W. R. (1967). Contact and Frictional Electrification. Oxford University Press.

Gallery

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  A cat demonstrating static cling with styrofoam peanuts.
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  A Hauksbee generator, an early device for generating static electricity.
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  Diagram showing asperities charged by the triboelectric effect.
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  The triboelectric series, showing materials ranked by their tendency to gain or lose electrons.
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  Example of a cyclic triboelectric series.
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  Diagram showing work function mismatch between gold and aluminum.
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  Schematic of a capacitor with a dielectric material.
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  Tribocharge generated from a sliding drop.
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  Warning sign for danger of static electricity.
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  Winglet of an Airbus A319-132, where static electricity can accumulate.
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  Antistatic wrist strap used to prevent electrostatic discharge.

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