26 RL Circuits: Voltage and Current Analysis in Circuits Containing Resistors and Inductors in Series
26.1 Introduction
In this chapter, we will examine RL series circuits formed by resistors and capacitors in series and what happens when these circuits are powered on or off.
26.2 Energizing
We have seen previously in this book that inductors hate current variations and will do everything to oppose the change by trying to block current increasing or pushing forward current decreasing.
Consider the circuit shown in Figure 26.1, composed of an inductor, a resistor, a voltage source, and a switch in series. The switch is initially open and the inductor is completely de‐energized.
At time t = 0 s, the switch is closed, and current flows from the voltage source and reaches the inductor.
However, like we have learned before, inductors hate sudden variations in current and create an electromotive force to oppose this new current to flow. This electromotive force will make a voltage rise across inductor with a polarity inverted in relation to V1. At the exact time the switch is closed, no current will flow across the inductor, and this component is seen by the circuit as an open circuit or as a resistor with a very large resistance.
As time passes, current gradually wins the battle against the electromotive force until the point where the electromotive force ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month, and much more.
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.
Julian F.
Head of Cybersecurity
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.
Addison B.
Field Engineer
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.
Amir M.
Data Platform Tech Lead
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.
