[PHY] Chapter 18 - D.C Circuits

DARRELL ER (COPYRIGHTED) © TOPIC 18: D.C CIRCUITS DARRELL ER (COPYRIGHTED) ©

CHAPTER ANALYSIS THE ABOUT TIME EXAM WEIGHTAGE DARRELL ER (COPYRIGHTED) ©

CIRCUIT DIAGRAM SERIES CIRCUIT PARALLEL CIRCUIT KEY CONCEPT DARRELL ER (COPYRIGHTED) ©

CIRCUIT DIAGRAMS DARRELL ER (COPYRIGHTED) ©

Series Parallel Current Current is the same throughout circuit. I1 = I2 = I3 Total current is sum of current in each separate branch. Itotal = I1 + I2 + I3 Potential Difference Total P .D is sum of P .D across each component. Vtotal = V1 + V2 Potential difference is the same across each branch. Vtotal = V1 = V2 = V3 SUMMARY TABLE DARRELL ER (COPYRIGHTED) © I1 I2 I3 Itotal V3 V2 V1 Vtotal V1 V2 Vtotal A1 A2 A3

Series Parallel Resistance Total effective resistance is sum of individual resistance. Rtotal = R1 + R2 + R3 Total effective resistance is sum of reciprocal of resistance in each branch. 1 / Rtotal = 1/R1 + 1/R2 + 1/R3 SUMMARY TABLE DARRELL ER (COPYRIGHTED) © R1 R2 R3 R2 R1 R3

A RIVER VISUALISATION How electricity works in a circuit is similar to a river. Current flows in a river and at times, it can split into smaller streams. When it does, the volume of water is reduced in each smaller stream. A parallel circuit works in the same way! Current will split into smaller volume as it enters each individual branch of the circuit. Itotal = I1 + I2 + I3 smaller stream, I2 BIG STREAM current direction current direction BIG STREAM DARRELL ER (COPYRIGHTED) © I1 I2 I3 Itotal

SERIES CIRCUIT Current is the same throughout circuit. I1 = I2 = I3 (There is only 1 big stream for the river) Total potential difference is sum of P .D across each component, as the current has to pass through all the resistors. Vtotal = V1 + V2 Total effective resistance is sum of individual resistance, as current has to pass through all the resistors. Rtotal = R1 + R2 + R3 SERIES CIRCUIT A disadvantage is that when one light bulb were to fuse, the entire circuit will no longer work. DARRELL ER (COPYRIGHTED) © V1 V2 Vtotal R1 R2 R3

PARALLEL CIRCUIT Total current is sum of current in each separate branch. Itotal = I1 + I2 + I3 (River splits into smaller streams, current will get divided as well) Potential difference is the same across each branch. V = V1 = V2 = V3 Total effective resistance is sum of reciprocal of resistance in each branch. 1 / Rtotal = 1/R1 + 1/R2 + 1/R3 PARALLEL CIRCUIT An advantage is that when one light bulb were to fuse the other parallel branches will still work. DARRELL ER (COPYRIGHTED) © I1 I2 I3 Itotal V3 V2