The resistance of a discharge tube is

The variation of current $(i)$ passing through a conductor as the voltage $(V)$ applied across its ends is varied is shown in the adjoining diagram. If the resistance $(R)$ is determined at the points $A, B, C$ and $D$,we will find that

Of the following graphs,the one that correctly represents the $I-V$ characteristics of an 'Ohmic device' is:

The $I-V$ graphs for two different electrical appliances $P$ and $Q$ are shown in the diagram. If $R_P$ and $R_Q$ are the resistances of the devices,then:

The $V-I$ graph for a conductor at temperatures $T_1$ and $T_2$ is as shown in the figure. $T_2-T_1$ is proportional to

The correct setup to verify Ohm's law is: