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Unit 4: Capacitors and Inductors in AC Circuits

In thi unit we’ll turn our attention to the behavior of capacitors and inductors in AC circuits. You saw in Unit 3 that resistors behave pretty much the same way in AC circuits as they do in DC circuits. But this is not true for capacitors and inductors. We use one set of rules (which you learned in EET 1150) for finding a capacitor’s voltage and current in DC circuits, and a different set of rules (which you’ll learn in this unit) for finding a capacitor’s voltage and current in AC circuits.

By the way, the rules that you learned in EET 1150 for finding the total capacitance and total inductance do hold for all circuits, DC or AC. But when you’re trying to figure out a capacitor’s current or voltage, you’ll use different techniques depending on whether the circuit is DC or AC.

AC circuit analysis relies heavily on trigonometry, which is the branch of mathematics dealing with angles. The last part of this e-Lesson covers some basic trigonometry, which you may have studied in a math class. But even if you’ve never studied trigonometry, you should be able to pick up this material without too much trouble.

Unit 3 Review

Capacitors in AC Circuits
Comparing Capacitors to Resistors
Phase Relationships in a Capacitor 
A Memory Aid: ICE
Capacitive Reactance
Ohm’s Law for Capacitors
Analyzing AC Capacitive Circuits
Not Ready Yet for AC Circuits with Capacitors and Resistors

Power in a Capacitor
True Power
True Power in a Capacitor
Reactive Power
Reactive Power in a Capacitor

Inductors in AC Circuits
Comparing Inductors to Resistors and Capacitors
Phase Relationships in an Inductor
A Memory Aid
Inductive Reactance
Ohm’s Law for Inductors
Analyzing AC Inductive Circuits
Not Ready Yet for AC Circuits with Inductors and Other Components

Power in an Inductor
True Power in an Inductor
Reactive Power in an Inductor
Quality Factor of an Inductor

Review of Electrical Quantities

Trigonometry Review
Angles & Quadrants
Negative Angles
Right-Angle Triangle
Three Kinds of Question
Question #1: Finding Unknown Side From Two Known Sides
Pythagorean Theorem
Fancy Names for the Sides of a Right-Angle Triangle
Question #2: Finding Unknown Side From Known Side and Known Angle
Trigonometric Functions: sin, cos, tan
Answering Question #2
Question #3: Finding Unknown Angle From Two Known Sides
Inverse Trigonometric Functions
Inverse Sine: sin-1
Inverse Cosine and Inverse Tangent: cos-1 and tan-1

Unit 4 Review

Congratulations! You’ve completed the e-Lesson for this unit.