State the meaning of electric current.
Define what is meant by electric potential difference (p.d.).
A power supply with e.m.f. $8.7\,\text{V}$ and negligible internal resistance is linked by two identical wires to three filament lamps, as shown in Fig. 5.1. The supply delivers a current of $0.30\,\text{A}$ to the circuit. The filament lamps are identical. The $I$-$V$ characteristic for one lamp is shown in Fig. 5.2.
Show that each connecting wire has a resistance of $2.0\,\Omega$.
The resistivity of the metal used for the connecting wires does not change with temperature. On Fig. 5.2, sketch the $I$-$V$ characteristic for one connecting wire.
Calculate the power lost in one connecting wire.
The following data for the connecting wires are provided below: cross-sectional area $= 0.40\,\text{mm}^2$ resistivity $= 1.7 \times 10^{-8}\,\Omega\,\text{m}$ number density of free electrons $= 8.5 \times 10^{28}\,\text{m}^{-3}$ Calculate the length of one connecting wire.
Calculate the drift speed of a free electron in the connecting wires.