Physics 9702 · AS & A Level · Resistance and resistivity

Resistance and resistivity — practice question

Uniform resistance wire AB is $50\text{ cm}$ long and has a diameter of $0.36\text{ mm}$. The metal used for the wire has resistivity $5.1 \times 10^{-7}\,\Omega\text{ m}$.
(a)[2]

Show that the resistance of wire AB is $2.5\,\Omega$.

(b(i))[4]

Wire AB is shown in Fig. 5.1 connected in series with a power supply $E$ and a resistor $R$. The e.m.f. of $E$ is $6.0\text{ V}$ and its internal resistance is negligible. The resistance of $R$ is $2.5\,\Omega$. A second uniform wire CD is joined across the terminals of $R$. CD has length $100\text{ cm}$, diameter $0.18\text{ mm}$ and is made from the same metal as AB. Calculate the current supplied by $E$.

(b)

Wire AB is shown in Fig. 5.1 connected in series with a power supply $E$ and a resistor $R$. The e.m.f. of $E$ is $6.0\,\text{V}$ and its internal resistance is negligible. The resistance of $R$ is $2.5\,\Omega$. A second uniform wire CD is connected across the terminals of $E$. CD is $100\,\text{cm}$ long, has diameter $0.18\,\text{mm}$ and is made of the same metal as AB.

(b(ii))[2]

Calculate the power transformed in wire AB.

(b(iii))[2]

Calculate the potential difference (p.d.) between midpoint $M$ on wire AB and midpoint $N$ on wire CD.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Formula used: $R = \rho l/A$

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