Electrostatics Overview

Electrostatics

• Electrostatics is a branch of physics studying stationary or slow-moving electric charges, the forces between them, the fields surrounding them, and their behavior in materials.
• The ancient Greeks observed that rubbing amber with wool could attract other light objects as early as 600 B.C.
• The word "electric" comes from the Greek word "elektron, meaning amber."
• Charge is neither created nor destroyed in any charging process; it's merely transferred from one body to another. This is called the Law of Conservation of Charge.

Objectives

• Define electrostatics
• Identify two types of charges.
• Identify methods of charging materials.
• Relate electrostatics to real-life situations.

Start-Up Questions

• What is the purpose of the third (round) prong on Type B plugs?
• What is the purpose of the holes in the pins of electrical plugs?

Electric Charge

• An atom in its stable/ground state has an equal number of protons and electrons.
• Protons have a positive charge.
• Electrons have a negative charge.
• Neutrons have no charge.
• Free electrons are not bound to any atom and participate in heat and electricity transfer.

Atom vs. Ion

• Atoms have equal numbers of protons and electrons, resulting in a neutral charge.
• An ion is an atom that has gained or lost an electron, resulting in a positive or negative charge.

Methods of Charge Transfer

• Friction: Rubbing materials cause electrons to transfer, charging the materials. Example: Comb and hair.
• Conduction: Contact between charged and uncharged materials transfers charge. Example: Balloon and a metal plate.
• Induction: A charged object can produce a charge in another object without contact, by inducing an opposite charge. Example: Charged rod and a neutral sphere.

Polarization

• Polarization is the separation of charges within a neutral object due to an external charged object.

Charge of Electron and Proton

• 1 electron = -1.6 x 10^-19 C
• 1 proton = +1.6 x 10^-19 C

Real-World Applications of Electrostatics

• Lightning: Thunderstorms separate charges, creating a large-scale discharge.
• Photocopying: Electrostatic charges attract toner particles to paper.