State Ohm's law. Draw a labelled circuit diagram to verify this law in the laboratory....

According to Ohm's law, when other physical parameters like temperature remain constant, the electric current flowing through a conductor is directly proportional to the potential difference across its two ends.
$V\infty I$
or $\frac{V}{I}=Constant=R$
or V =IR
Thus, the ratio V : I is a constant. This constant called the resistance (R) of the conductor. Circuit diagram for Ohm's law :
Explanation : If a graph is drawn between the potential difference (V) and current (I), the graph is found to be a straight line passing through the origin. This shows that the current is directly proportional to the potential difference.
Calculating the slope of the graph, $\frac{V}{I}=\frac{0.4}{0.1}=4=R$
Thus, the ratio $\frac{V}{I}$ remains constant. The slope of the V-I diagram gives the resistance (R) of the conductor.