Electrical Resistance
and Ohm’s Law
Electric circuits are used to
convert electrical energy into
some other form of energy
we need.


The devices we
use to convert the
electrical energy
are called electrical
loads.
As the electrons
flow through the
circuit, they
transfer energy to
the material in the
electrical load.
 The
ability of an electrical load to
impede the flow of electrons is
called electrical resistance, and the
loss of electric potential (voltage)
across the electrical load is called
potential difference (voltage drop).
The symbol for resistance is ‘d
ohm R=‘d
 The
relationship between the
potential difference across a
conductor and the electric current
flowing through it is called Ohm’s
law.
A
short circuit occurs when the
positive and negative terminal of a
source of electrical energy are
connected together by a good
conductions with very low
resistance.
 This
can cause a very large current
to flow from the source and may
generate so much heat that fires can
occur.
 Short
circuits can occur in many
different ways.