Define the potential difference (p.d.).
A power supply with e.m.f. $240\,\text{V}$ and no internal resistance is linked to a heater, as shown in Fig. 6.1. Each wire connecting the heater to the power supply is $75\,\text{m}$ long. The wires have a cross-sectional area $2.5\,\text{mm}^2$ and resistivity $18\,\text{n}\Omega\text{ m}$. The heater has a constant resistance of $38\,\Omega$.
Show that each wire has a resistance of $0.54\,\Omega$.
Calculate the current flowing in the wires.
Calculate the power dissipated in the wires.
The heater leads are replaced with wires of the same length and material, but with a cross-sectional area of $0.50\,\text{mm}^2$. Without doing any more calculations, state and explain the effect on the power loss in the wires.