TF EIM Chapt1

Fundamentals

Charge

Every stable and independent object (particle) that has charge has been observed to contain a quantized unit of charge which is a multiple of $1.6 \times 10^{-19} Coulombs$

What are the obervations/experiments?

Experiment 1: Matter is composed of Atoms with a positively charged nucleus surround by negatively charged electrons. If we now the charge of one mole of electrons ($F$= Faradays constant) and the number of electrons in a mole ($N_A$ = Avagadros number)then the charge of a single electron is given by

$e = \frac{F}{N_A}$

Experiment 2: Oil drop experiment

Experiment 3: The Hall Effect and the Josephson Effect

Electric Field

Two charged object separated by a distance (D) will feel a force between them known as the coulomb force. The magnitude of this force has been experimentally shown to be

$\left | \vec{F}_{coul} \right | = \frac{1}{4 \pi \epsilon_0} \frac{q_1 q_2}{r^2}$

where

$\varepsilon_0 =\frac {1}{\mu_0 c_0^2}=8.854187817 \times 10^{-12}$F/m

= a experimentally measured quantity satisfying the above relationship know as the permittivity of free space.

This force may be described in terms of an electric field E such that

$\vec{E} = \frac{\vec{F_q}}{q}$

Where

F= force between the objects

A separated object of finite charge creates an electric field.

Ohm's Law

resistance is a constant

$R = \frac{\Delta V}{I}$= constant

Voltage

The MKS unit for Voltage is a Joule per Coulomb $\left ( \frac{\mbox{J}}{\mbox{C}}\right )$

Voltage in circuits is typically defined as the electric potential energy per unit charge relative to ground.