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
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 (
= Faradays constant) and the number of electrons in a mole ( = Avagadros number)then the charge of a single electron is given byExperiment 2: Oil drop experiment
Experiment 3: The Hall Effect and the Josephson Effect
- Coulomb
- The amount of charge that flows through any cross section of a wire in 1 second if there is a steady current of 1 ampere in the wire.
Coulomb Force
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
where
- F/m = a experimentally measured quantity satisfying the above relationship know as the permittivity of free space.
- charge of first object
- charge of second object
- distance between the charges
(Charles Augustin Coulomb first measured the attract and repulsive force between two charged objects using a torsion balance around 1785)
This force may be described in terms of an electric field E such that
Where
- F= force between the objects
Electric Field
Vector Field
A separated object of finite charge creates an electric field.
Electric potential
Ohm's Law
- resistance is a constant
- = constant
Voltage
The MKS unit for Voltage is a Joule per Coulomb
Voltage in circuits is typically defined as the electric potential energy per unit charge relative to ground.