Electricity and Electric Current
This document covers the fundamental concepts of electricity and electric current. It addresses the nature of
electric current, Ohm's law, resistance and conductivity, the effects of temperature, series and parallel
circuits, as well as Kirchhoff's laws. Practical applications such as rheostats and thermistors are also
discussed.
by Wali Khan
, Nature of Electric Current
Electric current is the flow of electric charges through a conductor. In metals, it is the free electrons that
move. Conventional current flows from the high potential to the low potential, while the actual flow of
electrons is in the opposite direction. The unit of measurement for current is the ampere, defined as the
passage of a charge of one coulomb per second through a cross-section.
The drift speed of electrons is relatively slow, on the order of a few millimeters per second, although the
electrical signal propagates almost at the speed of light.
Random Motion 1
Without an electric field, electrons move
randomly.
Application of a Field
2
An electric field is applied, creating a force
on the electrons.
Directed Motion 3
Electrons move in the direction opposite to
the field, creating a current.
This document covers the fundamental concepts of electricity and electric current. It addresses the nature of
electric current, Ohm's law, resistance and conductivity, the effects of temperature, series and parallel
circuits, as well as Kirchhoff's laws. Practical applications such as rheostats and thermistors are also
discussed.
by Wali Khan
, Nature of Electric Current
Electric current is the flow of electric charges through a conductor. In metals, it is the free electrons that
move. Conventional current flows from the high potential to the low potential, while the actual flow of
electrons is in the opposite direction. The unit of measurement for current is the ampere, defined as the
passage of a charge of one coulomb per second through a cross-section.
The drift speed of electrons is relatively slow, on the order of a few millimeters per second, although the
electrical signal propagates almost at the speed of light.
Random Motion 1
Without an electric field, electrons move
randomly.
Application of a Field
2
An electric field is applied, creating a force
on the electrons.
Directed Motion 3
Electrons move in the direction opposite to
the field, creating a current.
