Physics 9702 · AS & A Level · Resistance and resistivity
Resistance and resistivity — practice question
A nichrome wire X, with a length of $45\,\text{cm}$ and a cross-sectional area of $4.7 \times 10^{-7}\,\text{m}^2$, is inserted into the circuit shown in Fig. 6.1. Wire X has a resistance of $1.1\,\Omega$. The cell provides an electromotive force (e.m.f.) of $1.3\,\text{V}$ and has negligible internal resistance.
(a(i))[1]
Calculate the current flowing in X.
(a(ii))[2]
In nichrome, the number density of charge carriers (electrons) is $8.5 \times 10^{28}\,\text{m}^{-3}$. Calculate the average drift speed of the charge carriers in X.
(a(iii))[3]
Calculate the resistivity of the nichrome wire.
(b(i))[2]
Wire Y is the same as wire X. Wire Y is connected in parallel with wire X, as shown in Fig. 6.2. State and explain any effect of this change on the ammeter reading.
(b(ii))[1]
State and explain any effect of this change on the average drift speed of the charge carriers in X.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct answer for current $I = 1.2\,\text{A}$” …