A student investigates an electrical circuit. The circuit is set up as shown in Fig. 2.1. A battery of negligible internal resistance is connected to a resistor of resistance $$\(Z\)$$. Five resistors, each of resistance $$\(R\)$$, are connected in parallel between P and Q . The switch is closed. The total current $$\(I\)$$ in the circuit is measured using the ammeter. The experiment is then repeated by changing the number $$\(n\)$$ of resistors, each of resistance $$\(R\)$$, connected in parallel between P and Q . It is suggested that $$\(I\)$$ and $$\(n\)$$ are related by the equation $$\[ E=I\left(\frac{R}{n}+Z\right) \]$$ where $$\(E\)$$ is the electromotive force (e.m.f.) of the battery. （c）（i）Plot a graph of $$\(\frac{1}{I} / 10^{3} \mathrm{~A}^{-1}\)$$ against $$\(\frac{1}{n}\)$$ ．Include error bars for $$\(\frac{1}{I}\)$$ ． ［2］ （ii）Draw the straight line of best fit and a worst acceptable straight line on your graph．Label both lines． ［2］ （iii）Determine the gradient of the line of best fit．Include the absolute uncertainty in your answer． gradient＝ ［2］ （iv）Determine the $$\(y\)$$－intercept of the line of best fit．Include the absolute uncertainty in your answer． $$\[ y \text {-intercept = } \]$$ .....................................................

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