A student investigates the resistivity of a wire using a circuit containing a cell of e.m.f. $ε\varepsilon$ and internal resistance $r$ , connected to an ammeter and a wire of length $L$ , diameter $d$ , and resistivity $ρ\rho$ . The relationship between the reciprocal of the current $1/ I$ and the length of the wire $L$ is given by:

\\frac{1}{I} = \\left(\\frac{4\rho}{\pi \varepsilon d^2}\\right) L + \\frac{r}{\varepsilon}

The student measures the cell's e.m.f. as $V\varepsilon = 2.00 \pm 0.10\text{ V}$ and determines the wire's diameter to be $\pm 0.008\text{ mm}$ . From a plot of $1I\frac{1}{I}$ against $L$ , the student determines the following parameters:

Gradient of the line of best fit = $m−16.20\text{ A}^{-1}\text{ m}^{-1}$
$y$ -intercept of the line of best fit = $A−10.50\text{ A}^{-1}$
Maximum $y$ -intercept from the line of worst fit = $A−10.85\text{ A}^{-1}$

\\frac{1}{I} = \\left(\\frac{4\rho}{\pi \varepsilon d^2}\\right) L + \\frac{r}{\varepsilon}

Gradient of the line of best fit = $m−16.20\text{ A}^{-1}\text{ m}^{-1}$
$y$ -intercept of the line of best fit = $A−10.50\text{ A}^{-1}$
Maximum $y$ -intercept from the line of worst fit = $A−10.85\text{ A}^{-1}$

Energy, power and resistance

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Energy, power and resistance

Question 2

Markscheme

Energy, power and resistance

Question 2

Energy, power and resistance Questions

Energy, power and resistance

Question 2

Energy, power and resistance Questions