Alternating Current Circuits

Based on Serway and Jewett

e6

CHAPTER OUTLINE

1 AC Sources2 Resistors in an AC Circuit3 Inductors in an AC Circuit

4 Capacitors in an AC Circuit5 The RLC Series Circuit6 Power in an AC Circuit

7 Resonance in a Series RLC Circuit8 The Transformer and Power Transmission

9 Rectifiers and Filters

Chapter Objectives

1-Describe alternating current (AC) circuits.2-Investigate the characteristics of simple series

circuits that contain resistors, inductors, and capacitors and that are driven by a sinusoidal voltage

3 -The illustration of the functions of some useful device such as transformers, power transmission, and electrical filters will be a conclusive end of this course.

1 AC Sources

2 Resistors in an AC Circuit

Phasor Diagram

Phasor diagram, R

AC terminology

The average value of thecurrent over one cycle is zero.But, does not matter with the resistance, R

P=i2RThe average value of the instantaneous current ,

The square root of the mean

Example

This equation states that an alternating current whose maximum value is 2.00 A delivers to a resistor the same power as a direct current that has a value of (0.707)(2.00 A) = 1.41 A. Thus, the average power delivered to a resistor that carries an alternating current is

When we speak of measuring a 120-V alternating voltage from an electrical outlet, we are referring to an rms voltage of 120 V. A quick calculation using Equation 33.5 shows that such an alternating voltage has a maximum value of about 170 V.

3 Inductors in an AC Circuit

Phasor diagram, L

IL lags behind vL

4 Capacitors in an AC Circuit

Phasor diagram, C

5 The RLC Series Circuit

6 Power in an AC Circuit

1/2 0

Power factor

7 Resonance in a Series RLC Circuit

A series RLC circuit is said to be in resonance when the current has its maximum value.

ASSIGNMENT

1-Redraw the resonance curves, I and P, using EXCELL software

2 -Read sections 33.8 and 33.9