In the circuit shown below (on the left) the resistance and the emf source are both variable. The graph of seven readings of the voltmeter and the ammeter ($V$ and $I$, respectively) for different settings of resistance and the emf, taken at equal intervals of time $\mathrm{\Delta }t$, are shown (on the right) by the dots connected by the curve $EFGH$. Consider the internal resistance of the battery to be negligible and the voltmeter and ammeter to be ideal devices. Take $R_0\equiv \frac{V_0}{I_0}$.

Then the plot of the resistance as a function of time corresponding to the curve $EFGH$ is given by