Download Chapter 20 – Circuits and Circuit Elements

Chapter 20 – Circuits and Circuit Elements
Schematic Diagrams and Circuits
pg 731
know the symbols for each of these components of a circuit (a path for electrons to
follow)
What is a circuit?
 Pg 732 for definition
 Does a lightbulb offer a complete conducting path? What are the components of a
lightbulb?
(a): charges
enter at the base
(b): go thru filament
(c): exit at threads
Series Circuits
 Resistors in series have the same current – all charges must flow through each
resistor
 The equivalent resistance in a series circuit is the sum of all of the circuits’
resistors:
Req = R1 + R2 + R3 + …..
 The Req is always greater than any individual resistance
 Series circuits require all elements to conduct – if one resistor is broken, no
current can flow and everything stops
Parallel Circuits
 Resistors in parallel always have the same potential difference (∆V) across them
 There is more than one path for the charges to flow
 The sum of the currents in parallel circuits equals the total current:
Ieq = I1 + I2 + I3 + …
The equivalent resistance is a reciprocal relationship:
1/Req = 1/R1 + 1/R2 + 1/R3 + …
Complex Circuits
 Resolve by isolating parts of a complex circuit until the equivalent resistance is
found…..
 Homework:
Practice 20-A Odd
Practice 20-B Odd
Practice 20-C Odd
Practice 20-D Odd