You set up the circuit shown in Fig. 26.20, where $C=5.00 \times 10^{-6} \mathrm{~F}$. At time $t=0,$ you close the switch and then measure the charge $q$ on the capacitor as a function of the current $i$ in the resistor. Your results are given in the table:
$$
\begin{array}{l|lllll}
i(\mathrm{~mA}) & 56.0 & 48.0 & 40.0 & 32.0 & 24.0 \\
\hline q(\mu \mathrm{C}) & 10.1 & 19.8 & 30.2 & 40.0 & 49.9
\end{array}
$$
(a) Graph $q$ as a function of $i .$ Explain why the data points, when plotted this way, fall close to a straight line. Find the slope and $y$ -intercept of the straight line that gives the best fit to the data. (b) Use your results from part (a) to calculate the resistance $R$ of the resistor and the emf $\mathcal{E}$ of the battery. (c) At what time $t$ after the switch is closed is the voltage across the capacitor equal to $10.0 \mathrm{~V} ?$ (d) When the voltage across the capacitor is $4.00 \mathrm{~V},$ what is the voltage across the resistor?