State what Kirchhoff’s second law says.
Three identical cells, each with electromotive force (e.m.f.) $1.5\,\text{V}$ and internal resistance $590\,\text{m}\Omega$, are arranged in parallel across a conductor, as illustrated in Fig. 5.1. The conductor has two cylindrical sections A and B. The circuit’s total resistance is $2.2\,\Omega$. Show that the conductor’s resistance is $2.0\,\Omega$.
Calculate the current flowing in the conductor.
The two cylindrical sections A and B of the conductor in Fig. 5.1 are made from the same material and are the same length. Section A has a diameter of $4.3\,\text{mm}$ and section B has a diameter of $7.6\,\text{mm}$. If their resistances are $R_A$ and $R_B$, calculate the ratio $\frac{R_A}{R_B}$.
Calculate the ratio of the average drift speed of free electrons in section A to that in section B. Explain how you arrived at your answer.
Sections A and B of the conductor in Fig. 5.1 are cylindrical, made from the same material and of equal length. Section A has diameter $4.3\,\text{mm}$ and section B has diameter $7.6\,\text{mm}$. Their resistances are $R_A$ and $R_B$.
The circuit in Fig. 5.1 is modified by removing one of the cells. State and explain what effect, if any, this has on the potential difference across the conductor.