Q123 / 197 · NEET 2009 (Mains) · Physics

A student measures the terminal potential difference (V) of a cell (of emf $\varepsilon$ and internal) resistance $r$ ) as a function of the current (I) flowing through it. The slope and intercept of the graph between $\mathrm{V}$ and $\mathrm{I}$, then respectively equal to :

  • A
    $-\epsilon$ and $r$
  • B
    $\in$ and $-r$
  • Correct answer
    C
    $-\mathrm{r}$ and $\in$
  • D
    $r$ and $-\epsilon$

Solution

$$ \begin{aligned} & \quad \mathrm{E}=\mathrm{V}+\mathrm{Ir} \\ & \Rightarrow \mathrm{V}=\mathrm{E}-\mathrm{Ir} \\ & \text { Comparing with } \mathrm{y}=\mathrm{mx}+\mathrm{c} \\ & \text { Slope }=-\mathrm{r} \text {, intercept }=\mathrm{E} \end{aligned} $$

Hence, the correct answer is option: 'C'.

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