Tru Physics

Static Electricity

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Tru Physics
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Introduction

Static electricity is a phenomenon where electric charges build up on the surface of a material, typically an insulator or a non-conductor of electricity. This accumulation of charge remains in one area rather than moving or flowing away, thus termed as ‘static’. The effect is usually caused by friction, where contact between surfaces results in the transfer of electrons.

Basic Principle

Static electricity is fundamentally a result of imbalance between negative and positive charges in an object. This imbalance can be generated by one of the following processes:

  • Triboelectric effect: This is the primary cause of static electricity, arising from friction between two different materials. When two surfaces touch and are then separated, an exchange of electrons occur between the surfaces that can leave an excess of electric charge on one surface.
  • Electrostatic induction: This is a redistribution of electrical charge in an object, caused by the influence of nearby charges.

The electric force between charged objects is described by Coulomb’s law:

F = k_e \dfrac{|q_1 \cdot q_2|}{r^2}

where F is the magnitude of the force between the charges, q_1 and q_2 are the charges, r is the separation between the charges, and k_e is Coulomb’s constant, 8.99 \times 10^9 \text{ Nm}^2/C^2.

Static Discharge

Static discharge can be a nuisance in daily life causing mild to severe shocks. In specific circumstances, it can be hazardous, such as in environments containing flammable gases or liquids. The spark resulting from a static discharge can ignite such substances.

Applications

Static electricity finds numerous applications in everyday life and in industrial processes. Some of the applications include photocopiers and laser printers where static electric charges attract the ink (or toner) particles onto the paper. Electrostatic precipitators in chimneys clean exhaust fumes of loose particles to reduce pollution. In painting processes, static electricity ensures a uniform coat.

Understanding static electricity also forms the basis for studying more complex electrostatic phenomena and is foundational in the field of electromagnetism.

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