CAPE Physics Unit 2 · 2015 · Paper 2 · Question 1(d)(ii)

The circuit in Figure 2 is set up with R_1 = R_3 = 4.0\text{ k}\Omega, R_2 = 1.0\text{ k}\Omega, and V_S = 20\text{ V}. R_x is a coil made from pieces of wire with diameter 0.6\text{ mm} of different lengths L. Values of V_{AB} and L are recorded in Table 1.

It can be shown that the equation in Part (c) can be approximated to V_{AB} = 4 - K\rho L, where K = 1.27 \times 10^5\text{ m}^{-2}\text{V }\Omega^{-1} and \rho is the resistivity of the coil wire. Use this equation and your graph to determine \rho, the resistivity of the coil wire.

This question uses a figure or table from the paper — you'll see it when you practise.