Chapter 18 Electric Forces + Electric Fields

Electric Charge

positive/negative, like charges repel and unlike charges attract one another, always conserved and only exchanged

Unit=Coulomb

Symbolized by e

e=1.6×10^-19 C

Conductors

materials in which the electric charges move freely, when charged in small region, charge readily distributes itself over entire surface of material

Example: copper/aluminum/silver

Insulators

materials in which electric charges do not move freely, when charged by rubbing, only rubbed area becomes charged

Example: glass/rubber/plastic

Semiconductors

characteristics of it are between those of insulators and conductors

Example: silicon/germanium

Proton

charge e+

positive charge

doesn’t move from one material to another because held firmly in nucleus

Electron

charge of e-

negative charge

gaining/losing electrons is how an object becomes charged, negative charge move from one object to another

Coulomb’s Law

the attraction of a particle is inversely proportional to the square of the separation between 2 particles and is along the joining line

Equation: F = k * (q₁ * q₂) / r²

K=9×10⁹ Nm²/C²

Polarization

the realignment of charge on the surface of an insulator, where the center of positive charge in neutral atoms or molecules may separate slightly in the presence of a charged object

Example: charged comb attracts bits of paper due to polarization of the paper

Charging by Conduction

when a charged object, like a rod, contacts a charged sphere, electrons move to the sphere, leaving the sphere with same charge as the charging object

Charging By Induction

requires no contact with the object inducing the charge, when a charged object attracts a neutral object, causing electrons to temporarily redistribute charges within the neutral object

Electric Field Pattern

a pattern of lines around a charged object; the lines indicate the direction a positively charged particle will move in the field

Electric Field of a Charge

the space around the charge in which an electric force due to that charge is experienced

3x^4+18=21x^2