Draw V-I Graph for both ohmic and non-ohmic materials stating one example of each as well.
Let's begin with the Ohm's Law
It states that the amount of current (I) flowing through a material (say a wire) is directly proportional to the voltage (V) applied across its ends. Mathematically, it is given as
V ∝ I
V = RI
here R is a constant of proportionality also known as the resistance. So, the resistance of a material following the Ohm's Law will always stay constant for all values of external voltage applied.
Now, using this principle, we can distinguish materials as either being Ohmic or Non-Ohmic in nature. Such that,
Ohmic materials follow the Ohms' law as the resistance remains unaffected even if we change the applied voltage (which alters amount of current flowing).
The V-I graph in this case shows a linear trend, as follows
A few examples include Nickel, Copper etc.
Non-Ohmic materials, as the name suggests, do not obey the Ohm's Law in its strictest sense as the resistance varies with applied voltage.
The V-I graph in this case would show a gradual curved slope, as follows
A few examples include Thermistor, Diode etc.