(g) DC circuits

Learning Objectives

 ·         draw circuit diagrams with power sources (cell, battery, d.c. supply or a.c. supply), switches, lamps, resistors (fixed and variable), variable potential divider (potentiometer) fuses, ammeters and voltmeters, bells, light-dependent resistors, thermistors and light-emitting diodes

·         state that the current at every point in a series circuit is the same and apply the principle to new situations or to solve related problems

·         state that the sum of the p.d.'s in a series circuit is equal to the p.d. across the whole circuit and apply the principle  to new situations or to solve related problems

·         state that the current from the source is the sum of the currents in the separate branches of the parallel circuit and apply the principle to new situations or to solve related problems

·         state that the potential differences across the separate branches of a parallel circuit is the same and apply the principle to new situations or to solve related problems

·         recall and apply the relevant relations, including R = V/I and those for potential differences in series and in parallel circuits, resistors in series and in parallel, in calculations involving a whole circuit

·         describe the action of a variable potential divider (potentiometer)

·         describe the action of thermistors and light-dependent-resistors and explain their use as input transducers in potential dividers

·         solve simple circuit problems involving thermistors and light-dependent resistors

An electric circuit is a complete or closed path through which electric charges flow from one terminal of an electrical source to the other, passing through one or more circuit components.