Unit II: Current Electricity

Electric current, the flow of electric charges in a metallic conductor, drift velocity and mobility, and their relation with electric current; Ohm’s law, electrical resistance, V-I characteristics (linear and non-linear), electrical energy and power, electrical resistivity and conductivity.Carbon resistors, colour code for carbon resistors; series and parallel combinations of resistors; temperature dependence of resistance.The internal resistance of a cell, potential difference, and emf of a cell, combination of cells in series and in parallel.Kirchhoff ’s laws and simple applications. Wheatstone bridge, metre bridge.Potentiometer – principle, and applications to measure potential difference, and for comparing emf of two cells; measurement of internal resistance of a cell.