CONCEPT MAP

The unit's concept map is rooted at Current Electricity and branches into four main strands. The first strand, Flow of Charges, branches further into drift velocity, current density and mobility -- the microscopic picture of how charge actually moves through a conductor. The second strand, Resistance, branches into Ohm's law and the V-I graph, resistivity, carbon resistors and their colour code, series and parallel combination, and the temperature coefficient of resistance -- everything to do with how a conductor opposes the flow of current and how that opposition can be measured, combined and predicted. The third strand, Kirchhoff's rule, splits into the current rule and the voltage rule, which together lead on to the Wheatstone's bridge and its practical applications (the metre bridge and the potentiometer) -- the systematic tools for analysing circuits too complex for Ohm's law alone. The fourth strand covers the two energy-conversion themes of the unit: the heating effects of electric current, leading to Joule's law of heating and its many applications, and the thermoelectric effects, splitting into the Seebeck effect, the Peltier effect and the Thomson effect. Together these four strands t …