1. ECE 4991 Electrical and Electronic Circuits Chapter 4

2. Where are we?
Chapter 2 - The basic concepts and practice at analyzing simple electric circuits with sources and resistors
Chapter 3 – More harder networks to analyze and the notion of equivalent circuits
Chapter 4 – Capacitors and inductors added to the mix
Chapter 5 – Analyzing transient situations in complex passive networks
Chapter 8 – New subject – the wonders of operational amplifiers as system elements
Chapter 9 – Introduction to semiconductors – the basics and diodes – more network analysis
Chapter 10 – Bipolar junction transistors and how they work – now you can build your own op amp

3. What’s Important in Chapter 4
Definitions, Concepts & Units
Capacitor characteristics
Inductor characteristics
LCR circuits in steady-state conditions

4. 1. Definitions, Concepts & Units
Capacitor
Farad
Dielectric
Capacitor i-v relationship
Capacitor energy storage
Inductor
Henry
Inductor i-v relationship
Inductor energy storage

5. 2. Capacitor Characteristics
A capacitor stores energy in an electric field
Electric field caused by separation of charge
Ideal Capacitor acts like an open with respect to DC current
Q = CV, or q(t) = Cv(t) ; Farad = Coul / Volt
But , so
Conversely, v(t) = + -

6. Combining Capacitors
Capacitors in series combine like resistors in parallel
Capacitors in parallel combine like resistors in series

7. Energy Storage in Capacitors
Energy is the integral of power, and P = IV
An RC circuit C R V

8. 3. Inductors An inductor stores energy in a magnetic field
Magnetic field caused by flow of current
Ideal inductor acts like a wire with respect to DC current
Maxwell’s equations + Lenz’s Law yields v= L (di/dt); Henry = V-s/A
Conversely,

9. Energy Storage in Inductors
Combining Inductors
Inductors combine like resistors
Energy Storage in Inductors
Energy is the integral of power

10. Working with Capacitors and Inductors - Combinations

11. Working with Capacitors and Inductors - Combinations

12. Working with Capacitors and Inductors – Currents/Voltages/ Energies

13. Working with Capacitors and Inductors – Currents/Voltages/ Energies

14. Working with Capacitors and Inductors – Transient Circuit AnalysisV R1 C

15. Working with Capacitors and Inductors – Transient Circuit AnalysisV R1

16. Working with Capacitors and Inductors – Steady State Circuit AnalysisV R1 C

17. Steady State Solutions
V = 8 volts, I = 2 amps, R1 = 16 ohms, R2 = 4 ohms, L = 2 H and C = 100 F. At t  ,
IR1 =
WC =
VL =
WL =
PR2 =
PV =

18. For Next Time
Practice problems – 4.1, 4.2 a &b, 4.4, 4.7, 4.10, 4.11, 4.15
Do some equivalent capacitance and inductance problems
Learn about Chapter 5
Writing differential equations for first-order circuits
Initial and final circuit conditions