Electrical resistance

The central idea is that of electrical resistance - what it is, how it can be measured, how it arises and what affects it. We begin by relating resistance to current and voltage through the electrical characteristics of various components (at the same time providing more practice in setting up electrical circuits and using ammeters and voltmeters). This will naturally introduce some of the key factors affecting resistance - choice of material, temperature, light intensity...

Next we investigate the temperature dependence of the resistance of metals and semiconductors and (where relevant) discuss the phenomenon of superconductivity and its applications. An investigation of the dependence of resistance on type of material and dimensions leads to resistivity. The electrical behaviour of different types of material can then be linked back to their microscopic structure.