As
per the earlier discussion on Ohms Law,
V = Applied
Voltage
R = Resistance
I = Current.
For
a constant temperature the resistance is a constant therefore the following
relationship can be obtained,
V α I
That
is that the Voltage applied is directly proportional to the current generated,
which directly means that the relationship is linear.
Consider
the following graph.
Here
the current has a linear relationship with voltage where the current is
linearly proportional to the voltage, hence it obeys the ohms law these types
of conductors are known as ohmic conductors.
Consider
the following relationship,
The
current and the Voltage does not have a linear relationship, that indirectly
that the resistance changes throughout the course of the change of voltage and
current therefore these conductors are called as non ohmic conductors.
Examples
for Ohmic and Non Ohmic Conductors..
Cu
wires conduct current linearly with the voltage that is if the voltage increase
then the current increases therefor it is an ohmic conductor.
Resistors
are also ohmic conductors since the too show the same characteristics.
Now consider the IV characteristics of a Diode.
Note
that the current and voltage does not show a linear relationship even under
forward or reversed biased conditions therefore diodes are considered as non
ohmic.
Consider
the I-V characteristic of a filament bulb,
Here
too the current and the voltage does not have a linear relationship the
resistance of the filament changes due to the increase in temperature therefore
it does not behave as per the ohms law hence it is considered to be non ohmic.
Some
other similar examples for non ohmic conductors are,
·
Thermistors
·
Crystal
Rectifiers
·
Vacuum Tubes
·
Semiconductors
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