Question

Draw the graph between Voltage (V) and Current (I) for ohmic and non-ohmic resistances.

Hint:

Remember that "Ohmic" means a linear V-I relationship (a straight line graph), while "non-ohmic" implies a non-linear relationship (a curved graph).

Answer 1

Step 1: Understanding the Concept: 
Ohmic resistances (or conductors) are those that obey Ohm's Law, which states that the current (I) through a conductor is directly proportional to the voltage (V) across it, provided the temperature and other physical conditions remain unchanged (\(V \propto I\)). 
Non-ohmic resistances are those that do not obey Ohm's Law. Their V-I relationship is not linear. 
Step 2: V-I Graph for Ohmic Resistance: 
According to Ohm's Law, \(V = IR\). If R is constant, this is the equation of a straight line passing through the origin, with the slope equal to the resistance R (\( \text{Slope} = \frac{\Delta V}{\Delta I} = R \)). 

Step 3: V-I Graph for Non-Ohmic Resistance: 
For non-ohmic devices, the resistance is not constant but changes with voltage or current. The V-I graph is a curve, not a straight line. Examples include semiconductor diodes, transistors, and thermistors. 

Graph Explanation:
Ohmic: A straight line through the origin indicates a constant ratio of V to I, meaning constant resistance.
Non-Ohmic: The curve shows that the ratio of V to I (the resistance) is not constant. The slope of the tangent at any point on the curve gives the dynamic resistance.