Greenridge Sec Physics 2024 Chap 18 Notes

Secondary Four (Express) Chapter 18 – DC Circuits Physics Notes - 1 - Prepared by: Mr Yong W. S. Greenridge Secondary School Secondary Four Express Physics Chapter 18 – D.C. Circuits (Notes Part 1) Name: ( ) Class: 4-8 Date: 5 April 2024 At the end of this chapter, you should be able to ☺ Draw circuit diagrams with power source (cell or battery), switches, lamps, resistors (fixed and variable), fuses, ammeters and voltmeters, bells, light-dependent resistors, thermistors and light-emitting diodes (LED). ☺ State that the current at every point in a series circuits is the same and apply to new situations or to solve related problems. ☺ State that the sum of the potential differences in a series circuits is equal to the potential difference across the whole circuit and apply 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 a parallel circuit and apply to new situations or to solve related problems. ☺ State that the potential difference in a parallel circuit to new situations or to solve related problems. ☺ Recall and apply the relevant relationship, 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 Additional Circuit Symbol Thermistor Light-Dependent Resistor Light-Emitting Diode (LED)

Secondary Four (Express) Chapter 18 – DC Circuits Physics Notes - 2 - Prepared by: Mr Yong W. S. SERIES Parallel Diagram Potential Difference Current Resistance

Secondary Four (Express) Chapter 18 – DC Circuits Physics Notes - 3 - Prepared by: Mr Yong W. S. Example 1 The circuit shown consists of a 12 V cell of negligible resistance. The ammeter measures a current of 0.5 A. Find (a) the p.d. across the 15  resistor (b) the p.d. across the resistor R (c) the value of resistor R Description Hybrid Diagram Current Potential Difference Resistance A 15  R 12 V

Secondary Four (Express) Chapter 18 – DC Circuits Physics Notes - 4 - Prepared by: Mr Yong W. S. Example 2 The circuit shown consists of 2 resistors of 4  and 2  connected in series. (a) What is the ammeter reading? (b) What is the potential difference across the 2  resistor? A 2  4  4 V

Secondary Four (Express) Chapter 18 – DC Circuits Physics Notes - 5 - Prepared by: Mr Yong W. S. Example 3 The