Physics 9702/33 — October/November 2011

Cambridge AS Level · Advanced Practical Skills · worked solutions for every part, with the mark scheme

questions

marks

120

minutes

Topics Manipulation, Measurement and Observation · Presentation of Data and Observations · Analysis, Conclusions and Evaluation

Q1Manipulation, Measurement and ObservationPresentation of Data and ObservationsAnalysis, Conclusions and EvaluationFree sample

In this experiment you will determine the resistivity of a metal in the form of a wire.

(a)

(i)

Measure and record the diameter $d$ of the short sample of wire that is attached to the card. You may remove the wire from the card.

$d$ = ______

(ii)

Calculate the cross-sectional area $A$ of the wire, in $\text{m}^2$ , using the formula

A = \frac{\pi d^2}{4}

$A$ = ______ $\text{m}^2$

(b)

(i)

Using the wire that is taped to the metre rule, set up the circuit shown in Fig. 1.1. Close the switch.

Fig. 1.1

(ii)

Position the crocodile clip Y approximately half-way along the wire.

(iii)

Measure and record the length $l$ of wire between the two crocodile clips and the voltmeter reading $V$ .

$l$ = ______
$V$ = ______

(c)

By moving crocodile clip Y, change $l$ and repeat (b)(iii) until you have six sets of readings of $l$ and $V$ for $l \geq 20\ \text{cm}$ . Include values of $\frac{1}{l}$ and $\frac{1}{V}$ in your table.

10M

(d)

(i)

Plot a graph of $\frac{1}{V}$ on the $y$ -axis against $\frac{1}{l}$ on the $x$ -axis.

(ii)

Draw the straight line of best fit.

(iii)

Determine the gradient and $y$ -intercept of this line.

gradient = ______
$y$ -intercept = ______

(e)

The quantities $V$ and $l$ are related by the equation

\frac{1}{V} = \frac{M}{l} + N

where $M$ and $N$ are constants.

(i)

Use your answers in (d)(iii) to determine values for $M$ and $N$ .

$M$ = ______ $\text{m V}^{-1}$
$N$ = ______ $\text{V}^{-1}$

(ii)

The resistivity $\rho$ of the material of the wire, in $\Omega\ \text{m}$ , can be found using the relationship

\rho = \frac{5 A N}{M}

Using your answers in (e)(i) and (a)(ii), calculate a value for $\rho$ .

$\rho$ = ______ $\Omega\ \text{m}$

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Q2Manipulation, Measurement and Observation · Analysis, Conclusions and Evaluation · Presentation of Data and Observations20M

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