I had to memorize all that stuff in order to get my US Extra class amateur radio license, but that doesn’t mean I truly understood it. Now I do. Thanks!
Glad you found it useful. I work with many electrical engineers who never really understood impedance, but deal with it all the time. Thanks for Subscribing.
Not an engineer of any kind, but used to play with antenna matching circuits and found this a superb little video, again I have never heard of the right angled triangle... Thank you.
That was almost first what we were taught in vocational school for electronics. If you continued to study at University level then you were teach how we got those formulas also same time we were taught complex numbers and some other fun math.
@@LimbaZero unfortunately no. I got a bachelors in EE. Our professors were the genius kind who know how to do but not how to teach lol they were dark times
I hate that youtube recommends EPIC videos like these AFTER I finish my courses on subjects that relate to it. If I would have come across these videos earlier, I would have passed my subjects with A's/HD's... Good video, I wish you were my lecturer or even private tutor!
Impedence was always so fascinating to me. The combination of capacitors and inductors creating resistance was something that was really satisfying to finally get.
If you have an interest in something, that's when you start to truly understand it. Many people shy away from Impedance, Power Factor and AC in general. Thanks for your comment.
The thing with the diagram showing a person being pushed through a tube, is that it's really just a visual for DC. For AC, it's more like pushing someone on a swing. That is, the electrons are really just moving back and forth in place; what flows through the tube is the signal to do so, like people in a stadium wave. Resistance is like the friction/air resistance that limits how high you can push the swing. Reactance, then, is a function of how efficiently you push them, given the frequency at which the swing resonates. If there's very little resistance but you push the swing at exactly the wrong times, impedance can still be very high (that is, you won't get the swing/current very high).
More confused - i lost total 'comprehension' (but not interest) exactly at the word "resonated", in "freq. at which the swing resonates. Even after assuming resonated simply referred to the 'tempo' the swing was returning back to the 'pusher'..
@@osearthesp The resonant frequency of an oscillator (to my understanding) is the frequency at which you vary the force/voltage to maximize the response (swing amplitude/current). If there's no air resistance / electrical resistance, the amplitude of the response will increase linear without bound at the resonant frequency (and nowhere else), but if there's even a tiny bit of resistance, the resonant frequency will simply approach some finite amplitude, and that will just be the largest available amplitude among frequencies of applying the same force.
In particular, the differential equation relating voltage and the rates of change of charge (incl. current) in an RLC series circuit takes the form of the equation for a damped harmonic oscillator: in this analogy where voltage is the driving force, it follows that capacitance is the (reciprocal of the) spring constant, resistance is the damping constant, and inductance is the mass. (In this model, without further considerations, a circuit with no inductance or capacitance--no mass, and no spring for simplicity--is assumed to respond instantly to voltage, like a swing that accelerates instantly to the speed at which air resistance exactly cancels the driving force)
A truly excellent explanation of inductance. You always know when you have a good teacher when you come away from something knowing you've truly understood the subject.
Many thanks for your comment. I'm please that so many people have found this video useful and I am truly humbled by all the great messages that people have kindly sent. I am very busy with my daytime job right now and have struggled to find time for further videos recently, but I promise more are coming. I have a long list of ideas to get through, so please keep an eye out and make sure you Subscribe.
@@paulpkae im 45 and have a software engineering degree i got almost 25 years ago and decided im going to start picking away at an ee degree. i have about 3 semesters worth of credits that carry over. i'm thinking about a few math courses. i have 3 of the six first term credits. i was going to take fluid dynamics, calculus or ee theory. i minored in business as my major was data mining algorithms and writing back end enterprise level software from scratch or automating the data from pre-relational databases and scrubbing it so it would load into an oracle backend or the like. one of my projects was taking a canadian revenue agency corporate business database written in power house and translating the fields into tables and automating primary/secondary/pregnant key generation. then i had to scrape a bunch of fortran files running on an old hp mini computer and populate the right tables with most likely mission critical data rank/ordered. it was like a rigorous version of data science people do using python now only i wrote most of it in functional c. the old borland c compiler. i ported duck hunt to run on dos because i was obsessed with dx7 when they made d3d and dinput more accessible. i played with open gl but it fixed function and no shader language yet. haha. i'd rather take rigorous courses first so i know i can do the math as i've been retired for a decade and lived and breathed ee as a hobbyist the whole time. what would you take, i have mental illness but no learning disability. i have not been in a stressful environment in years though. you seem like a nice person to ask as you're very smart. im interested in embedded development, writing drivers or asics using fpgas. i've done the nand to tetris thing but that's no verilog. haha. i've taught myself alot of math to make silly games but never really understood it. i've been doing a university level geometry course in my spare time so i have a leg up and plan to review physics as well. been forever since i took rigorous math but i understand all the ee circuit based math i've learned. thanks for the vids.
Resistance vs. Reactance: Resistance is a fundamental property of a material or component that opposes the flow of electric current. It depends on physical characteristics like the material's resistivity, length, and cross-sectional area. For example, a resistor with a certain value (say, 10 ohms) will always resist current by that amount, regardless of the type of current (AC or DC). Reactance, on the other hand, is an *emergent* property in AC circuits. It doesn't come from the physical characteristics alone but from the way capacitors and inductors interact with the changing AC signals. Reactance depends on the frequency of the AC signal and the phase difference between voltage and current. In other words: Resistance is like a steady, predictable barrier to current flow. Reactance is like a dynamic barrier that changes with the frequency of the AC signal Reactance is a type of resistance that only occurs in components like capacitors and inductors, which are found in AC (alternating current) circuits. Unlike regular resistance (like you find in a resistor), which simply resists the flow of electric current, reactance is a bit more complex because it depends on how the voltage and current interact over time. In a capacitor, the current leads the voltage. This means the current changes direction before the voltage does. In an inductor, it's the opposite: the voltage leads the current, so the voltage changes direction before the current. This difference in timing, or "phase," between the voltage and current creates what we call reactance. Because of this phase difference, the voltage and current don't reach their maximum values at the same time. This makes the ratio of voltage to current (V/I), which we call impedance in AC circuits, change. Here's how it works in simple terms: Capacitive Reactance (Xc): In capacitors, the current leads the voltage. So, at any given moment, the current is ahead of the voltage in its cycle. This "leads to" a certain kind of resistance called capacitive reactance. Inductive Reactance (Xl): In inductors, the voltage leads the current. So, the voltage is ahead of the current in its cycle. This results in a different kind of resistance called inductive reactance. Both types of reactance affect how AC circuits behave, but they do it in ways that depend on the frequency of the AC signal. Higher frequencies increase inductive reactance but decrease capacitive reactance, and vice versa. So, reactance is like resistance, but it’s special because it comes from the phase difference between voltage and current in capacitors and inductors. Imagine resistance as a speed bump on a road - it's always there, and it always slows down cars (current) by the same amount. Now, think of reactance as a wave on the ocean. The resistance to a boat's movement (current) changes depending on the wave's height and speed (the AC signal's frequency). If the waves are high and fast, the boat might struggle more (inductive reactance). If the waves are small and slow, the boat has an easier time (capacitive reactance). So, reactance emerges from how the waves (AC signals) interact with the boat (capacitors and inductors), while resistance is just the speed bump's fixed, unchanging opposition to the car's movement (current).
Then there's the semiconductor effect where (for a PN junction) the voltage has to exceed a certain point before current flows. Phil Hartley blew my mind when he pointed out that the energy is in the fields and the fields are in the substrate, not the copper. Thinking in terms of fields, I've been able to design much more effecient pcbs.
Speed bumps affect cars dynamically in that if they are hit at great speed or at an angle the vehicle could lose control or take major damage. I loved your comment clarifying reactance. However my mine is such that I find myself questioning points.
You missed something big: Resistance "consumes" irreversibly the energy (turned into heat). Reactance doesn't, it stores and restores. So reactance is something "like a resistor" that doesn't consumes energy. German has three words that make this clear: - Wirkleistung - Blindleistung - Scheinleistung In English i don't know but it is the S²=P²+Q²
@@rdson1621 same with a capacitor. An ideal one anyway. A real inductor does lose a little energy as heat but unless it’s going into space I think we can usually ignore that.
@@marcdraco2189 Who would have thought of that! Yeah I'm sarcastic. Let's go further: a conductuor actually isn't a conductor, it's an impedance ^^ Cheers from an electrical engineer.
7 หลายเดือนก่อน +13
This is the best explanation of impedance, I've ever heard! I loved all the analogies and how it was all easy to follow with no shortcuts being made. Brilliant, thank you for this!
I didn't understand these concepts well for months, but after watching this video, I understood them very well Please make more videos. You explain very well😍
If only my math teachers told me this when I was in school, I would have understood it. All they had to mention was "You can easily calculate all kinds of things with speakers and amplifiers" and I would have paid attention.
Thanks for the comment. I never learnt well at school, it was only when I started working and self studying did I really feel I was understanding things.
Thanks for the comment, much appreciated. Another video is on its way but, as an EE, it may not be your thing. Its all about the 555 chip and how I consider it to NOT be a Timer! ........
This is the best video I've seen on this topic. Great examples and demonstrations. Very well done! This is the first video I watched of yours and can't wait for more. If you need ideas I would love a detailed video on CTs. Thanks!
Trigonometry, wow. Simple trigonometry you say. I had difficulty with basic math in school. What in the world am I doing watching a video about trigonometry? I have memorized XL=2pyeFL and XC=1 0ver 2pyeFC. I have also memorized Z, Impedance and what that is. Phase angles are another story. All of this is exciting to learn and watch in practice. I can't believe I'm saying this. I worked at the Power Company Substation division for many years. Phase Angles came up often but I'll admit I looked past it. Our relay techs took care of it. I did learn in electronics school about the current and voltage leading or lagging in circuit. Your video is fabulous. Thanks. Hope I didn't bore you with my life time adventures.
Thanks for the comment. Most people don't really need to understand phase angle in their mainstream jobs even if you are working with electronics. I have many good engineers that have never really looked into it. In my view, its good to get an understanding of something like this, at least once and even if you then forget the detail you will always recall the basics and the concepts.
I remember "Eli the Ice Man" in college "E for Voltage Leads Current" in an Inductive circuit and "I for Current Leads Voltage" in a Capacitive Circuit.
I am super happy I chose to watch this. As a A Level Physics teacher, I found your explanation perfect - you are helping lots of people with this video :)
I've been trying to understand impedance for a while. I've watched many videos on the subject, but finally I understand it and how it all relates. Thank you.
ok most of the first 3 quarters of the video you were explaining something that I found somewhat interesting, but then you pulled out the triangle chart and completely blew my mind. I would never have guessed that you can use trigonometry to calculate the impedance and phase angle of a circuit. Great video!
I try to avoid overcomplicating with maths, but it always remains an important aspect. I will be doing further videos on the impedance triangle and explain why this works and will also lead into what Power Factor is. Thanks for watching and thanks for the comment.
@@pulsedmotor that meter is an NTi Audio Minirator MR PRO. Its a combined Impedance Meter & Signal Generator, with a few other functions. It's a professional grade meter that is commonly used in my profession as a PAVA engineer (Public Address & Voice Alarm).
Brilliant! Ditto all of the complimentary comments. This particular point (reactance) has eluded me since barely passing my electronics class 40-some years ago. I get it now. AWESOME. Thank you!!
Excellent description, as with many other commenters, I feel that I finally understand impedance. I've read and re-read this in books so many times, I thought I'd never get it. Thank you very much
Very fluidly explained. Every word of the video sinks in phase with our understanding of latent resistances that we have in daily life electrical and electronic circuits. Well described, thank you.
Brilliant video! Most of my knowledge about electrical circuits comes from the high school and it was mostly about DC. AC was never treated as much important. I knew there is something like impedance but had no idea how it relates to the resistance. Now it is clear for me. What I lack here is maybe the explanation for what we're using impedance. I think it can be used in Ohm's law for AC but would be great to see that on the video.
im not an electrical engineer or anything just a hobbyist, and impedance was just one of the things i new how to deal with but didnt rly have much of a grasp of, this video helped loads and i love the right triangle trick!
Very clear explanation! I jumped into electronics as a hobby a few years ago. I've probably read all of this at some point. I even have an LCR meter and know that reactance can change with frequency, but i never had an intuitive understanding of this until now. Your description and visualizations really helped me tie it all together. Thanks!
@scottduckworth3299 Thanks, that's exactly what I was hoping for with this video. To reach people who deal with impedance, but struggle to understand it or visualise what's going on.
What a great video. Such a basic concept that I didn't know. I feel embarrassed about how simple it is. Also. So cool that the phase shift works out to be the acute angle in the triangle. Blew my mind!
I stumbled onto this video completely randomly, but just wanted to highlight something cross-disciplinary: I studied structural engineering and there was one mandatory electrical engineering course that covered the subject of the video. It struck me then that the differential equation governing the RLC circuit has *exactly* the same form as that for structural dynamics with mass, stiffness, and viscous damping: mx''(t) + cx'(t) + kx(t) = F(t) And to further drive that home, the analogies you used for capacitance and inductance were stiffness and mass, respectively. Math and physics truly are beautiful!
Thanks for the comment. The similarities across all sciences are indeed very interesting. I always believe that there's some underlying universal rule that governs everything and it's probably very simple. Humans have simply just not discovered it yet.
Yes. very nicely explained. I hope people who are new to impedance learned something. I definitely learned how to keep things simpler when explaining :D
All the videos on TH-cam. Not sure if it's because I'm a millennial but videos like this one helps to keep the study flow going when mentally ill. Greatful
The analogies were super helpful! Pumping a tire and the flywheel. Now I understand why my friend who studied electrical engineering suggested a coil for a low pass filter.
Well done. I will have to watch it again (perhaps a couple of times) to bring this all on board, but I felt I understood it every step along the way. Very good teaching.
4:00 in the morning, and you're clear enough to keep me awake and interested. I would have gotten more from my freshman physics class 30+ years ago if you'd been my prof. I especially appreciated the mechanical analogies of the bicycle pump and the flywheel which gave me something I could understand immediately and will remember for the rest of my life. I do wish that, having derived the impedance, current, and phase angle of your circuit, you had set it up and shown the measurement as you did for the single components.
Liked, subscribed, and I would like to congratulate you, it's the best lecture on the subject's basics I've ever seen or read. You're a terrific communicator.
This vodeo popped up when I was looking for something else.... Brilliant description of Z. My first studies were to complete a Ship's Radio Officer course about 1969. This subject very much part of those studies. However, you were totally at the mercy of the Lecturer's description and understanding of the subject The whole course was by dictation... Nevermind videos! reference books were very hard to come by.... apart from some Post Office enineering publications. A few years later I completed a HND in Elects. Dictation and scribbling like mad was still order of the day... Years later when having a clean out, i came across some of the HND notes and had to laugh when I noticed in a chapter on Transistors. Every place where I should have written Transistor, I had written Transisto. The lecturer was a Geordie.😆
I am really, really liking this video, and I am subscribing. I got to the 14 minute mark and in the example you have an inductor which you describe as being "0.2 microHenrys". You know a LOT more about this stuff than I do, but I think you meant to say "0.2 milliHenrys" because the value you used was not based on a millionth but on a thousandth.
Yes, unfortunately I spotted this a few days after uploading. If you enable captions you will see I added some pop up text at that point. Thanks for the comment and thanks for Subscribing; much appreciated.
Great vid Paul, nicely explained ! AC Theory did and still does my head in :( one thing that's useful to know and sticks in my head from college, looooooong time past, was those little formula's like V/IR and relevent here is ICE (Current Leads Voltage In A Capacitive Circuit) and ELI (Voltage Leads Current In An Inductive Circuit) Enjoying your Vids. Les
That's made it really clear. Thanks and an immediate subscription. It would nice if you set up the final example on the bench and let us see what your impedance meter says.
Brilliant! This video could not be improved upon. I wish you had videos explaining everything related to electronics! I have read and read and read about this but until now, I never understood it. Thank you!
@@paulpkae Paul, you mentioned early on in the video around 9 minutes in that the -89 degrees shown on the meter is the phase angle. But at the end of the video you show that the phase angle is Sin(O/H) which works out to 15.7. It is not practically possible for that angle to ever be 89 degrees since the right triangle would only have 1 degree left over. Can you help me understand the large disparity between the 15.7 number you calculated and the 89 shown on the meter? Was it just because you were showing the capacitor's phase angle alone early in the video versus the entire circuit combined at the end?
@@Wil_Bloodworth brilliant question. You are obviously thinking about this quite deeply, which is great! The -89 degrees reading the meter gave early on in the video was during testing the impedance of an almost entirely capacitive circuit. i.e. just the capacitor connected across the terminals. I say 'almost' because there are always parasitic properties at play, and even though we only had a capacitor connected, there would have been a very small amount of DC resistance and some inductance too. That said, the capacitive reactance of this particular test circuit, would have been by far the most significant factor impeding the current flow. The impedance triangle would therefore be incredibly steep, almost infinitely. The impedance triangle near the end of the video however, was based on the imaginary circuit which incorporated a capacitor, inductor and resistor. It's phase angle was therefore much shallower and derived by the lengths of the adjacent and opposite sides. I do hope this makes it clearer for you. Thanks again for watching and your great comments.....Regards
Impedance, reactance, phase angles,etc have always been a bit of a struggle for me... it's not that much of a problem because I rarely visit the land of AC. This video has done a wonderful job of simplifying things to the degree where I might actually have a grasp on it now. (with a good few hints as to how low-pass and high-pass filters work too) :)
Thanks for the comment. Yes, once you understand "Reactance" and it's relationship with frequency, then High/Low Pass filters are much easier to understand.
I love the way you explain things. You should get a textbook on electric circuit theory and make videos explaining all of it, a playlist of dc then a playlist of ac 😅
While inductive reactance contributes to the transformer's impedance and helps limit the inrush current, other protection mechanisms like current limiters and thermal overload protection are more critical in preventing the transformer from burning out during startup. Also, the load on the secondary coil.
Thanks, my channel is relatively new and small. It seems the TH-cam algorithm has just started to notice my content. I do intend ramping up this channel significantly in the near future. Make sure you Subscribe and watch this space.......
Excellent video. Well done. Towards the end I was only hoping you'd return back to the speaker example, and in a few words explain why the impedance is much higher than resistance. Is a speaker's capacitative or inductive impedance high?
Typical speakers are 4 or 8ohms impedance. The one I was demonstrating was actually a 100V Public Address speaker which incorporates a step down transformer and a DC blocking capacitor.
I *finally* understand impedance. Thank you. This is probably one of the best videos I've ever seen on TH-cam.
Thank you. I'm pleased you found it of use.
Impedance is both Resistance and Reactance.
Seconded
Thirded
Fourthed
Help me step-electron, I'm stuck
Someone watches too much porn.
@@ericharrison6418 if you know, then that someone might be you
@@ericharrison6418 someone thinks too hard about obvious jokes
Fun fact: due to the wave-like nature of the electron, it can just "teleport" outside of wherever it's stuck 🤓.
@@Scotty-vs4lf My friend that wans't good at all
I had to memorize all that stuff in order to get my US Extra class amateur radio license, but that doesn’t mean I truly understood it. Now I do. Thanks!
Great! Thanks for the comment.
I'm an electrical engineer. The right triangle trick is genius. I can't believe we were never taught that. Subbed
Glad you found it useful.
I work with many electrical engineers who never really understood impedance, but deal with it all the time.
Thanks for Subscribing.
Not an engineer of any kind, but used to play with antenna matching circuits and found this a superb little video, again I have never heard of the right angled triangle... Thank you.
That was almost first what we were taught in vocational school for electronics. If you continued to study at University level then you were teach how we got those formulas also same time we were taught complex numbers and some other fun math.
@@LimbaZero unfortunately no. I got a bachelors in EE. Our professors were the genius kind who know how to do but not how to teach lol they were dark times
Should have gone to a better school. Sounds like you didn't learn phasors.
I hate that youtube recommends EPIC videos like these AFTER I finish my courses on subjects that relate to it. If I would have come across these videos earlier, I would have passed my subjects with A's/HD's... Good video, I wish you were my lecturer or even private tutor!
Thanks for the comment, much appreciated.
we need to create an AI based on him .....
@@testing-nj2ne fuck AI. just donate amd praise the real person
Impedence was always so fascinating to me. The combination of capacitors and inductors creating resistance was something that was really satisfying to finally get.
If you have an interest in something, that's when you start to truly understand it. Many people shy away from Impedance, Power Factor and AC in general. Thanks for your comment.
The thing with the diagram showing a person being pushed through a tube, is that it's really just a visual for DC. For AC, it's more like pushing someone on a swing. That is, the electrons are really just moving back and forth in place; what flows through the tube is the signal to do so, like people in a stadium wave. Resistance is like the friction/air resistance that limits how high you can push the swing. Reactance, then, is a function of how efficiently you push them, given the frequency at which the swing resonates. If there's very little resistance but you push the swing at exactly the wrong times, impedance can still be very high (that is, you won't get the swing/current very high).
Thanks. Another great description.
After reading this comment and then imagining the impedence triangle in a situation where there's no phase angle it finally clicked for me.
More confused - i lost total 'comprehension' (but not interest) exactly at the word "resonated", in "freq. at which the swing resonates. Even after assuming resonated simply referred to the 'tempo' the swing was returning back to the 'pusher'..
@@osearthesp The resonant frequency of an oscillator (to my understanding) is the frequency at which you vary the force/voltage to maximize the response (swing amplitude/current). If there's no air resistance / electrical resistance, the amplitude of the response will increase linear without bound at the resonant frequency (and nowhere else), but if there's even a tiny bit of resistance, the resonant frequency will simply approach some finite amplitude, and that will just be the largest available amplitude among frequencies of applying the same force.
In particular, the differential equation relating voltage and the rates of change of charge (incl. current) in an RLC series circuit takes the form of the equation for a damped harmonic oscillator: in this analogy where voltage is the driving force, it follows that capacitance is the (reciprocal of the) spring constant, resistance is the damping constant, and inductance is the mass.
(In this model, without further considerations, a circuit with no inductance or capacitance--no mass, and no spring for simplicity--is assumed to respond instantly to voltage, like a swing that accelerates instantly to the speed at which air resistance exactly cancels the driving force)
A truly excellent explanation of inductance. You always know when you have a good teacher when you come away from something knowing you've truly understood the subject.
Many thanks for your comment. I'm please that so many people have found this video useful and I am truly humbled by all the great messages that people have kindly sent.
I am very busy with my daytime job right now and have struggled to find time for further videos recently, but I promise more are coming. I have a long list of ideas to get through, so please keep an eye out and make sure you Subscribe.
@@paulpkae im 45 and have a software engineering degree i got almost 25 years ago and decided im going to start picking away at an ee degree. i have about 3 semesters worth of credits that carry over. i'm thinking about a few math courses. i have 3 of the six first term credits. i was going to take fluid dynamics, calculus or ee theory. i minored in business as my major was data mining algorithms and writing back end enterprise level software from scratch or automating the data from pre-relational databases and scrubbing it so it would load into an oracle backend or the like. one of my projects was taking a canadian revenue agency corporate business database written in power house and translating the fields into tables and automating primary/secondary/pregnant key generation. then i had to scrape a bunch of fortran files running on an old hp mini computer and populate the right tables with most likely mission critical data rank/ordered. it was like a rigorous version of data science people do using python now only i wrote most of it in functional c. the old borland c compiler. i ported duck hunt to run on dos because i was obsessed with dx7 when they made d3d and dinput more accessible. i played with open gl but it fixed function and no shader language yet. haha.
i'd rather take rigorous courses first so i know i can do the math as i've been retired for a decade and lived and breathed ee as a hobbyist the whole time. what would you take, i have mental illness but no learning disability. i have not been in a stressful environment in years though. you seem like a nice person to ask as you're very smart. im interested in embedded development, writing drivers or asics using fpgas. i've done the nand to tetris thing but that's no verilog. haha. i've taught myself alot of math to make silly games but never really understood it. i've been doing a university level geometry course in my spare time so i have a leg up and plan to review physics as well. been forever since i took rigorous math but i understand all the ee circuit based math i've learned. thanks for the vids.
I am an Electrical Engineer. I used this as a refresher. Thank you.
Brilliant. Glad you found it useful.
I’m an electrician and this is one of the key subjects in the school part of our education, it’s so very key to understand electricity
Resistance vs. Reactance:
Resistance is a fundamental property of a material or component that opposes the flow of electric current. It depends on physical characteristics like the material's resistivity, length, and cross-sectional area. For example, a resistor with a certain value (say, 10 ohms) will always resist current by that amount, regardless of the type of current (AC or DC).
Reactance, on the other hand, is an *emergent* property in AC circuits. It doesn't come from the physical characteristics alone but from the way capacitors and inductors interact with the changing AC signals. Reactance depends on the frequency of the AC signal and the phase difference between voltage and current.
In other words:
Resistance is like a steady, predictable barrier to current flow.
Reactance is like a dynamic barrier that changes with the frequency of the AC signal
Reactance is a type of resistance that only occurs in components like capacitors and inductors, which are found in AC (alternating current) circuits. Unlike regular resistance (like you find in a resistor), which simply resists the flow of electric current, reactance is a bit more complex because it depends on how the voltage and current interact over time.
In a capacitor, the current leads the voltage. This means the current changes direction before the voltage does. In an inductor, it's the opposite: the voltage leads the current, so the voltage changes direction before the current.
This difference in timing, or "phase," between the voltage and current creates what we call reactance. Because of this phase difference, the voltage and current don't reach their maximum values at the same time. This makes the ratio of voltage to current (V/I), which we call impedance in AC circuits, change.
Here's how it works in simple terms:
Capacitive Reactance (Xc): In capacitors, the current leads the voltage. So, at any given moment, the current is ahead of the voltage in its cycle. This "leads to" a certain kind of resistance called capacitive reactance.
Inductive Reactance (Xl): In inductors, the voltage leads the current. So, the voltage is ahead of the current in its cycle. This results in a different kind of resistance called inductive reactance.
Both types of reactance affect how AC circuits behave, but they do it in ways that depend on the frequency of the AC signal. Higher frequencies increase inductive reactance but decrease capacitive reactance, and vice versa.
So, reactance is like resistance, but it’s special because it comes from the phase difference between voltage and current in capacitors and inductors.
Imagine resistance as a speed bump on a road - it's always there, and it always slows down cars (current) by the same amount.
Now, think of reactance as a wave on the ocean. The resistance to a boat's movement (current) changes depending on the wave's height and speed (the AC signal's frequency). If the waves are high and fast, the boat might struggle more (inductive reactance). If the waves are small and slow, the boat has an easier time (capacitive reactance).
So, reactance emerges from how the waves (AC signals) interact with the boat (capacitors and inductors), while resistance is just the speed bump's fixed, unchanging opposition to the car's movement (current).
Then there's the semiconductor effect where (for a PN junction) the voltage has to exceed a certain point before current flows.
Phil Hartley blew my mind when he pointed out that the energy is in the fields and the fields are in the substrate, not the copper. Thinking in terms of fields, I've been able to design much more effecient pcbs.
Speed bumps affect cars dynamically in that if they are hit at great speed or at an angle the vehicle could lose control or take major damage.
I loved your comment clarifying reactance. However my mine is such that I find myself questioning points.
You missed something big:
Resistance "consumes" irreversibly the energy (turned into heat).
Reactance doesn't, it stores and restores. So reactance is something "like a resistor" that doesn't consumes energy. German has three words that make this clear:
- Wirkleistung
- Blindleistung
- Scheinleistung
In English i don't know but it is the S²=P²+Q²
@@rdson1621 same with a capacitor. An ideal one anyway. A real inductor does lose a little energy as heat but unless it’s going into space I think we can usually ignore that.
@@marcdraco2189 Who would have thought of that! Yeah I'm sarcastic. Let's go further: a conductuor actually isn't a conductor, it's an impedance ^^ Cheers from an electrical engineer.
This is the best explanation of impedance, I've ever heard! I loved all the analogies and how it was all easy to follow with no shortcuts being made. Brilliant, thank you for this!
Thanks for such a great comment, much appreciated.
Best introduction to impedance that I have seen in 30 years. Even gives me a new way to explain it.
Many thanks for watching and even more so for your comment.
You are the best teacher I have ever seen. If I had had a teacher like you when I was a teenager, I would be a great engineer today.
Many thanks, that's a great comment to receive, much appreciated.
I've been trying to understand bioimpedance for over a year now. Somehow, in a half hour, it makes so much more sense to me. THANK YOU!
I don't know how many times I've learned about this, but now, finally I understand it; thank you!
Great, I'm glad it's helped.
I didn't understand these concepts well for months, but after watching this video, I understood them very well
Please make more videos.
You explain very well😍
Thanks for your comment, it's very much appreciated. I'm glad these videos are reaching the right audience.
This is the best impedance explanation video ever made. Thank you so much for sharing your knowledge.
You're very welcome! And thanks for the comment.
If only my math teachers told me this when I was in school, I would have understood it. All they had to mention was "You can easily calculate all kinds of things with speakers and amplifiers" and I would have paid attention.
Thanks for the comment. I never learnt well at school, it was only when I started working and self studying did I really feel I was understanding things.
Finally, all of my questions are answered and I am not confused about impedance anymore. Thank you so much. You are an amazing teacher.
Great to hear! Thanks for watching and thanks for the comment. Be sure to Subscribe more videos coming including a follow up to this Impedance one.
I’m an EE. That was a great talk. Looking forward to more like this.
Thanks for the comment, much appreciated. Another video is on its way but, as an EE, it may not be your thing.
Its all about the 555 chip and how I consider it to NOT be a Timer! ........
Took me too long to understand impedance. This explanation finally got me.
That's great. Thanks for watching and for your comment.
This is the best video I've seen on this topic. Great examples and demonstrations. Very well done! This is the first video I watched of yours and can't wait for more. If you need ideas I would love a detailed video on CTs. Thanks!
Thanks for your comment. I will put your suggestions onto my list.
Trigonometry, wow. Simple trigonometry you say. I had difficulty with basic math in school. What in the world am I doing watching a video about trigonometry? I have memorized XL=2pyeFL and XC=1 0ver 2pyeFC. I have also memorized Z, Impedance and what that is. Phase angles are another story. All of this is exciting to learn and watch in practice. I can't believe I'm saying this. I worked at the Power Company Substation division for many years. Phase Angles came up often but I'll admit I looked past it. Our relay techs took care of it. I did learn in electronics school about the current and voltage leading or lagging in circuit. Your video is fabulous. Thanks. Hope I didn't bore you with my life time adventures.
Thanks for the comment. Most people don't really need to understand phase angle in their mainstream jobs even if you are working with electronics. I have many good engineers that have never really looked into it. In my view, its good to get an understanding of something like this, at least once and even if you then forget the detail you will always recall the basics and the concepts.
I remember "Eli the Ice Man" in college "E for Voltage Leads Current" in an Inductive circuit and "I for Current Leads Voltage" in a Capacitive Circuit.
I am super happy I chose to watch this. As a A Level Physics teacher, I found your explanation perfect - you are helping lots of people with this video :)
Wow, thank you!
Brilliant! Epic! I needed this video about 50 years ago! All the best, Rob in Switzerland
Thanks. Glad you likes it. Sorry it's a bit late for you :)
Resistance, impedance and reactance are all forms of opposition to current flow. Thank you sir for this insightful video
Thanks for watching and thanks for your comment.
What a wonderful introduction to complex numbers
I've been trying to understand impedance for a while. I've watched many videos on the subject, but finally I understand it and how it all relates. Thank you.
Glad it helped!
This was the first video about impedance I watched and I am so glad I did. Phenomenal job at explaining it! Thanks a bunch!
Glad it was helpful! Thanks for commenting.
I think that’s one of the best explanation I have ever seen. Fantastic video 👍🏻
Glad it was helpful, and thanks for the comment.
ok most of the first 3 quarters of the video you were explaining something that I found somewhat interesting, but then you pulled out the triangle chart and completely blew my mind. I would never have guessed that you can use trigonometry to calculate the impedance and phase angle of a circuit.
Great video!
I try to avoid overcomplicating with maths, but it always remains an important aspect.
I will be doing further videos on the impedance triangle and explain why this works and will also lead into what Power Factor is.
Thanks for watching and thanks for the comment.
@@paulpkae Thanks for the video! I greatly enjoyed it
Great video and explanation. I especially loved the phase angle from the triangle.
Thanks for the comment.
@@paulpkaewhat is the meter you use. Is it some kind of signal generator?
@@pulsedmotor that meter is an NTi Audio Minirator MR PRO. Its a combined Impedance Meter & Signal Generator, with a few other functions. It's a professional grade meter that is commonly used in my profession as a PAVA engineer (Public Address & Voice Alarm).
i love your teaching style , thankyou very much
Brilliant! Ditto all of the complimentary comments. This particular point (reactance) has eluded me since barely passing my electronics class 40-some years ago. I get it now. AWESOME. Thank you!!
Thank you. Glad it's helped.
Same here 25 years ago😂
Excellent description, as with many other commenters, I feel that I finally understand impedance. I've read and re-read this in books so many times, I thought I'd never get it. Thank you very much
That's brilliant! Thanks for the comment, it makes the effort all worthwhile.
I teach electonics I really liked how he built the explanation up.
Thanks for your comment. I plan to publish more videos like this soon. Make sure you Subscribe.
Very fluidly explained. Every word of the video sinks in phase with our understanding of latent resistances that we have in daily life electrical and electronic circuits. Well described, thank you.
@@mansurbhamani3905 thanks. Brilliant comment.
Fantastic explanation. Clear and concise without moving too fast.
Glad you enjoyed it!
This is amazing, very clear explanation
Thank you for your comment.
Brilliant video! Most of my knowledge about electrical circuits comes from the high school and it was mostly about DC. AC was never treated as much important. I knew there is something like impedance but had no idea how it relates to the resistance. Now it is clear for me. What I lack here is maybe the explanation for what we're using impedance. I think it can be used in Ohm's law for AC but would be great to see that on the video.
Thanks for the comment. Glad you found it useful.
Amazing explanation! This is one of the best videos on impedance!
Many thanks.
Very clear and concise explanation with great analogies and proof on the bench.
Much appreciated!
im not an electrical engineer or anything just a hobbyist, and impedance was just one of the things i new how to deal with but didnt rly have much of a grasp of, this video helped loads and i love the right triangle trick!
Brilliant, glad it has been helpful.
One of the clearest explanation i have seen.
Thank you very much..
My doubts are all clear.
Thanks. Glad you liked it. Hopefully you Subscribed 😁
👏Great video, well explained
Thanks, much appreciated.
Very clear explanation! I jumped into electronics as a hobby a few years ago. I've probably read all of this at some point. I even have an LCR meter and know that reactance can change with frequency, but i never had an intuitive understanding of this until now. Your description and visualizations really helped me tie it all together. Thanks!
@scottduckworth3299 Thanks, that's exactly what I was hoping for with this video. To reach people who deal with impedance, but struggle to understand it or visualise what's going on.
What a great video. Such a basic concept that I didn't know. I feel embarrassed about how simple it is. Also. So cool that the phase shift works out to be the acute angle in the triangle. Blew my mind!
Thanks for watching and thanks for the comment. Glad you found it informative.
This is the best video explaining electronic concept I have ever watched! Thanks for making this video.
Glad you liked it and many thanks for your comment.
Your effort and excellent explanation deserves more appreciation and subscriptions!!👍🏻👍🏻
I stumbled onto this video completely randomly, but just wanted to highlight something cross-disciplinary:
I studied structural engineering and there was one mandatory electrical engineering course that covered the subject of the video.
It struck me then that the differential equation governing the RLC circuit has *exactly* the same form as that for structural dynamics with mass, stiffness, and viscous damping: mx''(t) + cx'(t) + kx(t) = F(t)
And to further drive that home, the analogies you used for capacitance and inductance were stiffness and mass, respectively.
Math and physics truly are beautiful!
Thanks for the comment. The similarities across all sciences are indeed very interesting.
I always believe that there's some underlying universal rule that governs everything and it's probably very simple. Humans have simply just not discovered it yet.
Not randomly. AI was watching your interests and offering appropriate videos.
@@Deus_Ex_Machina. the algorithm works correctly sometimes then. :)
Yes. very nicely explained. I hope people who are new to impedance learned something. I definitely learned how to keep things simpler when explaining :D
Thanks.
All the videos on TH-cam. Not sure if it's because I'm a millennial but videos like this one helps to keep the study flow going when mentally ill. Greatful
Glad it's helped in some way. Thanks for commenting.
Ohh yeah!!! Thanks a lot for this video!!! Right triangle for phase explaination is great!
Thanks for watching and especially the comment.
This is very similar to the way I thought about reactance! The analogies are spot on. Great video! Thank you for putting this together
Thanks for watching and the comment. Much appreciated and glad you found it useful.
The analogies were super helpful! Pumping a tire and the flywheel.
Now I understand why my friend who studied electrical engineering suggested a coil for a low pass filter.
Thanks. These helped me too. I am simply sharing the knowledge and passing it on.
Brilliant!!! Such great examples, visuals, comparisons to make this all make sense!!!
@@panepinto1959 thank you. Glad you enjoyed it.
Brilliantly explained and very well delivered. Thank you
Glad you enjoyed it!
Thank you for taking the time to explain the concept in a very intuitive way!
Glad it was helpful and thanks for your comment.
I already knew about this subject, but it was a cristal clear explanation, I will sent it to my friends so they can learn too, thank you!
That's great thank you. Make sure they all Subscribe too :)
Thank you for this! Definitely one of the better impedance videos I've seen. I would have loved to have seen this when I started EE.
Many thanks.
Well done. I will have to watch it again (perhaps a couple of times) to bring this all on board, but I felt I understood it every step along the way. Very good teaching.
Thank you. Yes, watching through a couple of times usually helps paint the picture better in your mind.
4:00 in the morning, and you're clear enough to keep me awake and interested. I would have gotten more from my freshman physics class 30+ years ago if you'd been my prof. I especially appreciated the mechanical analogies of the bicycle pump and the flywheel which gave me something I could understand immediately and will remember for the rest of my life. I do wish that, having derived the impedance, current, and phase angle of your circuit, you had set it up and shown the measurement as you did for the single components.
Thanks for the comment. Yes that would have been good to include.
Excellent, simple and intuitive explanation. Well done!
Thanks for the comment. New video on it's way today..... Keep an eye out for it.
I love that illustration with the three, now four, guys! Very helpful analogy.
Very useful. Don't understand much about circuits but this helped illuminate reactive power a little, I think. Thank you :)
Thanks for the comment.
that's easily a semester worth of knowledge in some parts of the world. great work!
Many thanks.
Clear, concise and with real world examples.
Thanks for the comment.
Linear and clear in all parts, thank you for your brilliant explanation!!?
Glad it was helpful!
Thank you, very vivid explanation! Love the bicycle pump and fly wheel analogies!
Glad you enjoyed it!
An inductor as a flywheel is brilliant! I am a student myself, but I do tutor some underclassmen, and I am using that analogy from now on.
Fantastic!
This is exactly what I needed to know for my project, thank you!
Glad it was helpful!
Liked, subscribed, and I would like to congratulate you, it's the best lecture on the subject's basics I've ever seen or read. You're a terrific communicator.
Many thanks for the comment and glad you found it useful.
probably the best explanation i've ever seen!!
Thanks very much.
This vodeo popped up when I was looking for something else.... Brilliant description of Z. My first studies were to complete a Ship's Radio Officer course about 1969. This subject very much part of those studies. However, you were totally at the mercy of the Lecturer's description and understanding of the subject The whole course was by dictation... Nevermind videos! reference books were very hard to come by.... apart from some Post Office enineering publications. A few years later I completed a HND in Elects. Dictation and scribbling like mad was still order of the day... Years later when having a clean out, i came across some of the HND notes and had to laugh when I noticed in a chapter on Transistors. Every place where I should have written Transistor, I had written Transisto. The lecturer was a Geordie.😆
Haha, Great story, thanks for sharing.
I am really, really liking this video, and I am subscribing. I got to the 14 minute mark and in the example you have an inductor which you describe as being "0.2 microHenrys". You know a LOT more about this stuff than I do, but I think you meant to say "0.2 milliHenrys" because the value you used was not based on a millionth but on a thousandth.
Yes, unfortunately I spotted this a few days after uploading. If you enable captions you will see I added some pop up text at that point.
Thanks for the comment and thanks for Subscribing; much appreciated.
I flunked this test years back....but all i needed was this video....😮
If only I published it sooner 😆
I wish you were my teacher when I was studying to be an electrician in the 1970’s. Well done.
Thanks, glad you enjoyed.
Excellent explanation.
Thank you, much appreciated.
Great vid Paul, nicely explained ! AC Theory did and still does my head in :( one thing that's useful to know and sticks in my head from college, looooooong time past, was those little formula's like V/IR and relevent here is ICE (Current Leads Voltage In A Capacitive Circuit) and ELI (Voltage Leads Current In An Inductive Circuit) Enjoying your Vids. Les
Cheers Les.
Awesome explanation. You’ve got a new subscriber. I like high quality contents and this video is a nice example of that.
Thanks for your comment and thanks even more for Subscribing.
Good video, well explained. Compiments to the instructor
Many thanks.
Excellent presentation of resistance, impendance and reactance. Thank you for the time being spent on that thing
Many thanks for your comment.
best explanation that i have ever watched, thank you very much sir
@@matthias7534 thanks for the comment. Much appreciated.
That's made it really clear. Thanks and an immediate subscription. It would nice if you set up the final example on the bench and let us see what your impedance meter says.
Thanks for watching & your comment and an even bigger thanks for Subscribing; much appreciated. More videos coming...
Thanks! Great explanations!
Glad you liked it and thanks for the comment.
Absolutely Brilliant!! First time understood these concepts... Thank you very much!! 😊
Thanks. I'm glad it helped.
What a incredible explanation. Thank you so much.
Many thanks for the comment.
Brilliant! This video could not be improved upon. I wish you had videos explaining everything related to electronics! I have read and read and read about this but until now, I never understood it. Thank you!
Thanks for your kind words. It means so much to get such feedback and makes all the effort worthwhile.
My pleasure. I'm on the winning end of this deal so please keep creating excellent content and I'll continue to provide positive feedback!@@paulpkae
@@paulpkae Paul, you mentioned early on in the video around 9 minutes in that the -89 degrees shown on the meter is the phase angle. But at the end of the video you show that the phase angle is Sin(O/H) which works out to 15.7. It is not practically possible for that angle to ever be 89 degrees since the right triangle would only have 1 degree left over. Can you help me understand the large disparity between the 15.7 number you calculated and the 89 shown on the meter? Was it just because you were showing the capacitor's phase angle alone early in the video versus the entire circuit combined at the end?
@@Wil_Bloodworth brilliant question. You are obviously thinking about this quite deeply, which is great!
The -89 degrees reading the meter gave early on in the video was during testing the impedance of an almost entirely capacitive circuit. i.e. just the capacitor connected across the terminals.
I say 'almost' because there are always parasitic properties at play, and even though we only had a capacitor connected, there would have been a very small amount of DC resistance and some inductance too.
That said, the capacitive reactance of this particular test circuit, would have been by far the most significant factor impeding the current flow.
The impedance triangle would therefore be incredibly steep, almost infinitely.
The impedance triangle near the end of the video however, was based on the imaginary circuit which incorporated a capacitor, inductor and resistor. It's phase angle was therefore much shallower and derived by the lengths of the adjacent and opposite sides.
I do hope this makes it clearer for you.
Thanks again for watching and your great comments.....Regards
@@paulpkae perfect! That's exactly what I needed. Thank you Paul!
Greta video! This helped me crystallize my understanding of impedance more than any of my electrical classes did
Thanks. The intention was indeed to help people better visualise this topic in their minds.
Impedance, reactance, phase angles,etc have always been a bit of a struggle for me... it's not that much of a problem because I rarely visit the land of AC. This video has done a wonderful job of simplifying things to the degree where I might actually have a grasp on it now. (with a good few hints as to how low-pass and high-pass filters work too) :)
Thanks for the comment.
Yes, once you understand "Reactance" and it's relationship with frequency, then High/Low Pass filters are much easier to understand.
I love the way you explain things. You should get a textbook on electric circuit theory and make videos explaining all of it, a playlist of dc then a playlist of ac 😅
Maybe one day! Thanks for watching and many thanks for the comment.
I FINALLY understand why transformers don't blow up when you plug them in! Inductive reactance! Hope I got that right. 👍 Excellent video!
While inductive reactance contributes to the transformer's impedance and helps limit the inrush current, other protection mechanisms like current limiters and thermal overload protection are more critical in preventing the transformer from burning out during startup. Also, the load on the secondary coil.
@@paulpkae I will look deeper into that. Thanks again!
Considering impedance as imaginary value resistors makes the reactance as a plain complex resistor, amazingly simplified with complexity!
Where were you all this time? Brilliant example, anyone can understand this, you put it in such simple terms, it shows your grasp on the concept. 👌
Thanks, my channel is relatively new and small. It seems the TH-cam algorithm has just started to notice my content. I do intend ramping up this channel significantly in the near future. Make sure you Subscribe and watch this space.......
This was an excellent explanation of impedance. It took me a long time to understand it in my own, and I wish I had found this video much sooner. 😊
Many thanks. Appreciate the comment.
Excellent video. Well done. Towards the end I was only hoping you'd return back to the speaker example, and in a few words explain why the impedance is much higher than resistance. Is a speaker's capacitative or inductive impedance high?
Typical speakers are 4 or 8ohms impedance. The one I was demonstrating was actually a 100V Public Address speaker which incorporates a step down transformer and a DC blocking capacitor.
I agree the perfect follow on to this excellent video would be examples where we see these scenarios are played out. Speakers and other components etc
very good explanation. I've always had a problem understanding impedance.
Thank you. I'm glad you found it useful.
great intro, thank you. i was always confused by the word "impedance" because it sounded similar to "resistance".
Thanks for watching and thanks for your comment.
Thank you very much, I'm learning the rlc circuit, and this just popped up in my feed, and this helped me alot
@@syphon5899 that's great to hear. Thanks.
Thank you, you explained this topic beautifully.
Glad it was helpful!
Thank you. This is a really good explaination