Hi all! If you do better reading things at your own pace, the transcript for this video, with the images embedded, is here: www.circuitbread.com/tutorials/how-does-an-led-work
Can someone please explain how energy is conserved when the photon is emitted? The valence electron passes from the n region to p region as a result of the voltage across the two regions supplied by the power supply-energy is conserved by producing a current (which is literally that transfer of the electron), makes sense. But when that valence electron emits the photon where does THAT energy come from? Is it being coming from the momentum of the electron as it is brought into orbit of an atom in the p region? Please explain... I cannot figure that part out. Amazing video!
kalki avatar (beast of the earth) (christ on the white horse) (son of man on clouds) is the biggest enemy of dajjal/antichrist/kali 😏 Kalki Avatar (Murtaza) cousin of Moula mahdhi a.s. (muhammad) 😎 Moula mahdhi is raja shashidhuvj 😎 Prophet Moula mahdhi and Moula Isa both will kill dajjal cause dajjal is going to kill Kalki Avatar 😏 Kalki Avatar will follow orders from 2 religious king Moula mahdhi a.s. and Moula Isa a.s. 😎 Kalki Avatar going to have 2 swords and ring of moula sulaiman a.s. and staff of moula musa a.s. (iron rod) Staff of moula musa a.s. is like omintrix can transform into anything and can transform others into anything And stone in the ring of moula sulaiman a.s. is also known as kastav mani and it's more powerful the all 6 infinite stones combined 😇 This staff will transforms into white horses with wings,weapons,iron-man,cloud etc or can do imagination into reality 😎 *Ratn sru sword of lord shiva (miri)😇 *Ratn varu (zulfakar) sword of Moula Ali (piri) 😇 miri piri 😇 Satyug (sunrise from West) 01.aug.38 😏 Gzwa e hind 2029 😎....
I'm an EE student and i gotta say my teachers really explain just because they need a paycheck. And at a stage i was like: damnnnn EE is boring but this channel totally proves me the otherwise. I just found it last night and i'm fascinated. Great job !!
Haha! That's awesome to hear! Yeah, EE can be boring in the wrong hands but I think we're fortunate that all of the engineers here at CircuitBread find it fascinating, which helps keep us motivated when things are challenging.
You could say a regular diode produces heat by emitting infrared. LEDs just have a different omposition which causes then to emit radiation with a smaller wavelength, e.g., visible light.
I have never been lost faster in a how-to video. I appreciate your credibility, but you might want to do another that explains what diodes are as well.
Hi there! We actually have several videos on diodes - a higher level video on how they work as well as several videos on how they work at the semiconductor level. Hopefully they clarify things!
It's interesting to read the comments from students regarding the good teaching styles on these types of videos. I've learned more on UA-cam from channels like this than I could have ever learned in school, where most Teachers (in my experience) quite obviously couldn't be bothered.
Teachers can be hit or miss, unfortunately. But there are great teachers out there that do really care about students, you just have to find them. And hope they're not burned out by being overwhelmed by students who yearn for help. One of the greatest professors I had as an undergraduate went above and beyond and, even ten years after I got my bachelors, was willing to help us with a handful of these semiconductor devices videos, making sure they're accurate. Those are the type of teachers and professors I'm grateful for.
Thank you! We're actually hoping, once we get more content up, to actively partner with colleges on some content so that students can have their in-class and our video/written tutorials work together. I don't know how well it will work out but that's something we're striving for.
Why LEDs look the way they do with the dome? I think it's just a manufacturing standard developed years ago that was easy to make and didn't block any of the light coming from the light emitting portion itself. There are many, many different body styles now available.
Interestingly enough, we have shot a video about how a computer works from the ground up - starting with sand and talking about how that's turned into semiconductors which are then turned into logic gates, etc. While the video is completely shot, there are a few animated portions of it that are being time consuming. I'm not sure if this is exactly what you're looking for but we're quite excited for this video to be published. Whenever it actually happens...
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors. ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
I think it would be more accurate to say the energy from electrons falling into holes in a rectifier diode are released as infrared photons. It becomes heat because most rectifier diodes have opaque black bodies.
Can someone please explain how energy is conserved when the photon is emitted? The valence electron passes from the n region to p region as a result of the voltage across the two regions supplied by the power supply-energy is conserved by producing a current (which is literally that transfer of the electron), makes sense. But when that valence electron emits the photon where does THAT energy come from? Is it being coming from the momentum of the electron as it is brought into orbit of an atom in the p region? Please explain... I cannot figure that part out. Amazing video!
You're right - it's when the electron goes into orbit of an atom in the p region, dropping in its orbital energy to do so. We say it "fills a hole" but the reality is that it's just dropping into the valence band, or, in other words, being pulled into orbit around a specific atom. The energy it loses from dropping into that hole is emitted as a photon, producing the light. Now, where I'm a bit sketchy and would rather have someone with a PhD or just better specialization in this field confirm, is that the electron *does* lose energy crossing the junction and getting onto the p-side, but then the electron loses *more* energy when it drops into orbit of the atom. I'll leave this out there if someone (including other engineers at CircuitBread) want to comment. Excellent question, thank you!
@@CircuitBread Thanks for the detailed response! That really clears things up for me. I do know that energy is conserved when the electron moves position as a result of the chain of electrons in the circuit simultaneously moving (that is, a current through the circuit) which takes energy from the battery. Think of a watering hose, if it is full of water (wire full of electrons) and you add some more water to it via a water supply (adding electrons to the wire with a CV source), water is immediately spilled out on the other end, thus the energy gained from forcing water into one end is conserved when water is spilled out the other end. Same concept with electron flow. With this in mind, I do not think that it is the individual electron loosing energy as it crosses into the p region, instead energy from that action is consumed in the battery as a new electron further down the line enters a charged terminal as another electron leaves the terminal of opposite charge.
@@greenief9097 can you please explain how electron energy is lowered when it goes to orbit around atom Since when electron is confined to move within an orbit it's Δ x is less, so Δ p should be more acc to uncertainty principle
@@CircuitBread can you please explain how electron energy is lowered when it goes to orbit around atom Since when electron is confined to move within an orbit it's Δ x is less, so Δ p should be more acc to uncertainty principle
@@pavanjoshi2448 Having taken a course on it since the time of my first reply, look into "potential energy wells." Specifically finite potential wells. It is a pretty abstract idea, and connects the wavelength of the electron to the energy it has. When the electron is passing from one atom to the next, it briefly inhabits free space. Think of a ball that has rolled down a hill and is resting at the bottom. But then, it comes within the vicinity of the next atom, and this is similar to saying that the ball now is near a ridge where it can fall down. As the electron falls into orbit, loosing the potential energy it had and gaining kinetic energy, it emits a photon of a specific wavelength to compensate for the energy change. This is not an in depth answer: look into potential wells!
I have a question.. is there a material of LED that can produce all wavelength? I mean, we just modification of voltage or something else to make different wavelength?
Not that I'm aware of - unless I've missed some update in some basic physics (and I'm not saying that sarcastically, there are constant updates in the scientific fields) then the wavelength of the emitted light is directly tied to the materials used in the LED.
At around 1:35ish, you discuss how for silicon diode, energy is released in the form of heat, whereas for led materials, the energy is released in the form of light. How come the difference in why one releases light and one releases heat ? Thanks
Yeah! It's all about the wavelength of the energy and how much of a drop in energy there is when the electron changes from one energy level to the other. This is actually how they have made LEDs of different colors - blue, a higher energy light, requires a greater energy drop of the electron than red light so they put together two materials where there is the appropriate change in energy level from one to the other. So, there are a few things going on here but if the electron drops a smaller step, like in a diode, the energy is in the infrared range and is trapped inside the device itself - heat!
He predicted the existence of electromagnetic waves but I'm not sure who it was that actually figured out which wave lengths produce ultraviolet light...
Maybe this is a dumb questions but how do the holes get replenished? It seems like they disappear when recombined but the LED doesn't really "run out" right?
No, not a dumb question at all, it's something I think all of us have considered at one point or another. My understanding is that it's just a matter of it being a true circuit - as the holes are filled with the electrons dropping into them, holes are forming elsewhere due to the energy being put into the system. The holes slowly move into place and replenish the lost holes. Since it's done constantly, there's never a real lack of holes. I need to reach out to my semiconductors expert again, she may have a more technically fulfilling way of describing it.
Dear sir, thanks for your explanation. I have one question on energy conservation in photo-diode. In case of LEDs, the battery is injecting high energetic electrons (from its negative terminal) to the conduction band at n- side and collecting low energetic electrons (by the positive terminal) from the valence band at p-side. So the battery is losing energy which is manifested as light(or heat). Can you please explain (by using electron/hole movement) how energy conservation is valid in photo-diode/photo detectors. In this case, when i am drawing the schematic diagram of electron-hole movement, it seems to me that the battery is getting the absorbed photon energy (I mean battery is getting high energy electron from the conduction band at n-side and releasing low energy electron at the valence band of p-side). How is it possible? How the battery can store the absorbed photon energy? I am doing something wrong.
I disagree, you aren't doing anything wrong - the battery WILL absorb the photon energy. A photo diode is, in essence, just a small solar cell. Depending on the setup, the current generated by the photodiode may go back into the battery or it may go elsewhere in the circuit. If the battery is non-rechargeable, hopefully it won't be going back into the battery but, at the same time, the amount of current these small photo diodes create are extremely small and probably non-problematic.
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors. ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
It is pretty crazy technology! It's not the amount of doping, it's by putting two different materials together that, when an electron moves from one to the other, it loses the exact amount of energy needed to create a photon of the color you want. Most diodes just produce heat when the electron loses that energy.
What happens when all the electrons cross and fill all the holes? what reiterates the process? Thanks (I have no idea how these things work but I find it very interesting)
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors. ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
this only confirms my thoughts, though vaguely... i want to believe the electron is being stripped into photons but since i myself am not an electron, i cannot actually see the process
3:15 I didn't understand why the lead frame shaped like this(like triangular plane)? Why not designed it like a column that holds the semiconductor material
Hey Amjad, I don't know but I have a theory I think is reasonable. The light emitting side is the cathode, so you want as much available surface area there as possible. However, a thin vertical bar would be pretty weak mechanically. So, by creating those two odd shapes, you're maximizing the surface area on top of the cathode while still providing enough mechanical strength to both the anode and the cathode to not be bent during the encapsulation process. A flaw in this thinking is that the wire between the anode and cathode is tiny and doesn't seem to be affected. Hmmm... I hope someone else that knows the answer will chime in.
I had that same question when I first learned about this. My understanding is that once the electrons drop in energy, then they act like a "normal" electron in that material, which means they can later jump into the conduction band and be conducted out of the device to go around the circuit loop again.
Sorry, what's a KTU syllabus? I'm getting "APJ Abdul Kalam Technological University" from a google search. We actually are trying to create our newer series to be more in line with general electronics syllabi but there's always going to be variations...
Can someone please check my understanding of what is going on molecularly. The voltage difference between the cathode and anode liberates a electron from the N type region of the diode. This electron finds a path to an empty positively charged hole in the P type region. However due to the composition of the molecules around that hole, the energy loss for that electron to fill that hole will be of the same size as the desired frequency. It therefore sheds this energy in this form of photon to fill the hole it is drawn to.
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors. ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
Yep, that was a question I had as well. What happens is that, since you have a voltage, those electrons drop into the holes on the other side of the PN junction and then those electrons (or, more likely, other electrons) eventually pop out of the holes again and work their way out of the semiconductor material to go around in a big cycle again. I recommend checking out our video on how a PN junction works to hopefully clarify this question.
The larger the energy gap, the higher the knee voltage. You'll note this with LEDs of different colors. Different band gaps generate different colors, which is why LEDs of different colors have different band gaps. I'm not sure if there's a mathematical relationship between the two but I would be a little surprised if there isn't.
I like the video's style and how greatly articulated and visualized the explanations are. Much disappointed though, as I expected an explanation of how "white" is created in such a video instead of having it only listed along the LED's inherent colours in the video with no reference of its creation in the details or later on.
Sorry about that! In one of our RGB videos, it is mentioned that typically white is created by emitting a balance of all three colors. There is also a way of making a blue LED more white with some sort of coating but I'm not as familiar with that process as much. Creating white with the three colors is a lot more primitive yet widespread than you'd think.
Silicon diodes actually DO emit light, as proven by that one time I accidentally shorted a diode and it lit up like a Christmas tree. It's just that the light produced by a diode is immediately blocked by the structure of the diode itself, which causes it to be absorbed.
I knew they emitted light, but I thought it was more in the red-infrared range. But yep, the opaque cover makes it so you can even see the little bit of light they do produce (under normal conditions). Thanks for sharing! It would've been cool to have gotten that on video.
I am wondering if LED lights emit the light a frequency so that your eyes percieve the light to less intense than the peak of each flash. Do LEDs flash on and off? Do you know if the human eye can detect this flashing? Does the brain then merge the flashes with the darkness inbetween and so percieve the light to be dimmer than the individual flashes but brighter than the darkness between these flashes?
LEDs, given a constant voltage, will give out a constant light. While the photons are discrete, there are so many of them, there is no way our brains could distinguish each one. On the other hand, a common way of dimming LEDs is exactly that method. They flicker the LEDs on and off fast enough that our brains can't register that they're flickering but instead interprets it as simply being dimmer. I have seen where they've flickered the LEDs too slowly and it gives a very subtle, nearly subconscious, strobing effect that is quite unpleasant.
@@CircuitBread damn, i hoped i was wrong. So you are agreeing, the led may appear less bright than it actually is, due to your brain merging the bright flash with the dark inbetween. I wonder if this means the retina or other sensitive parts of the eye may be more easily damaged by this LED light as the light is maybe brighter than the retina or optic nerve is percieving it.
I've wondered about that myself - it seems like if the flash were bright enough, even if the duration is incredibly short, then it would cause some damage.
Exactly! The LED is optimized to create light from power and a solar cell is optimized to create power from light but practically, it's the same thing happening in reverse.
Not really... as they're not designed for that, they could burn out open or burn out closed, which means that they could make the situation even worse. There may be fuses that incorporate LEDs to indicate their status - I haven't heard of that but there's a lot of things that exist that I haven't heard of.
@@CircuitBread my new lamp At night I close it When I look at it on the roof it's off course I see a little light like a small dot After some time it finishes I got scared
Hm, interesting. Strangely, LEDs are so efficient that they can emit a very small glow with small amounts of residual charge or stray voltage. While this can cause a glow to last a ridiculously long time (minutes), it is common for LED bulbs to take several seconds to wind down to a level that you can no longer see them.
The subatomic space dragg is less negative for it to expand in to for us to see light. 😍 than we are the ones losing photons 😍🤣😭😍 Breeee nice This conformation. 👀 bit than man don't see the difference between photons en cosmic behaviure jad😅🌈
No mention of how LEDs work as the reverse of the photovoltaic effect? In the photovoltaic effect, an electron is freed from a low energy state by absorbing a photon; LEDs work by releasing an photon by an electron falling into a low energy state.
We discussed it but we ended up deleting that from the script because we didn't think we could do it justice without getting too deep into the physics behind it. We could've been wrong about that assumption.
So is the light emitted unpolarized light (I hope it is; polarized light is bad for health, I've heard). Also, do you know of any lead and arsenic-free LEDs? I've been looking all over the web... These simple ones don't, but do many of the lights marketed as LEDs emit any UV? I just had to ditch the idea of lighting my future home with Sodium Vapour Lamps because they contain mercury... Bioluminescent lights haven't evolved much yet... If only there was a lead-and-arsenic-free LED...
LEDs emit unpolarized light but most all of them contain trace amounts of lead and arsenic. The quantities of these materials are extremely small, though, and while not ideal, is generally much more environmentally and biologically friendly than many other options. That is assuming you're using high-quality LEDs from a reputable source - some LED manufacturers may be less focused on following environmental regulations. In regards to UV, unless the LEDs are specifically designed to emit UV, their emissions in that spectrum are minimal to non-existent. That's one reason they're popular as outdoor lights - their limited heat and UV output makes it so they don't attract bugs like incandescent bulbs do.
But I think future science teaching will give stress on its practical side instead of teaching those electon proton theories. Where gallium is found and how it is placed in a LED knowing that is more important
I think that these fields will become more stratified and specialized. I think there will always be people who need to know the electron/photon theories so they can improve the underlying technology, while others will be focused on sourcing and purifying materials and fabrication methods. Just like Arduino has made it so that many people can jump right into embedded systems with limited electronics understanding but we still need the people who create the Atmega processors the Arduino is built on, as well as the library the IDE is built on.
Thanks for the feedback! Could you let me know exactly which symbols were flipped? I only see three in the reference table and I *think* they're right. I appreciate you keeping us honest!
I've heard this concern and have even read a research paper about it that seemed inconclusive. I'm not a biologist or a doctor, so I can't say anything definitive on the physiological side. But, from an engineering point of view, I haven't come across anything that would make the think that LED technology is inherently worse for the eyes.
Not 100% sure I understand the question but if you remember that photons are just little packets of energy, not actual matter, that should help. So, instead of emitting energy as heat, it's emitting it as light.
kalki avatar (beast of the earth) (christ on the white horse) (son of man on clouds) is the biggest enemy of dajjal/antichrist/kali 😏 Kalki Avatar (Murtaza) cousin of Moula mahdhi a.s. (muhammad) 😎 Moula mahdhi is raja shashidhuvj 😎 Prophet Moula mahdhi and Moula Isa both will kill dajjal cause dajjal is going to kill Kalki Avatar 😏 Kalki Avatar will follow orders from 2 religious king Moula mahdhi a.s. and Moula Isa a.s. 😎 Kalki Avatar going to have 2 swords and ring of moula sulaiman a.s. and staff of moula musa a.s. (iron rod) Staff of moula musa a.s. is like omintrix can transform into anything and can transform others into anything And stone in the ring of moula sulaiman a.s. is also known as kastav mani and it's more powerful the all 6 infinite stones combined 😇 This staff will transforms into white horses with wings,weapons,iron-man,cloud etc or can do imagination into reality 😎 *Ratn sru sword of lord shiva (miri)😇 *Ratn varu (zulfakar) sword of Moula Ali (piri) 😇 miri piri 😇 Satyug (sunrise from West) 01.aug.38 😏 Gzwa e hind 2029 😎....
Hi all! If you do better reading things at your own pace, the transcript for this video, with the images embedded, is here: www.circuitbread.com/tutorials/how-does-an-led-work
Can someone please explain how energy is conserved when the photon is emitted? The valence electron passes from the n region to p region as a result of the voltage across the two regions supplied by the power supply-energy is conserved by producing a current (which is literally that transfer of the electron), makes sense. But when that valence electron emits the photon where does THAT energy come from? Is it being coming from the momentum of the electron as it is brought into orbit of an atom in the p region? Please explain... I cannot figure that part out. Amazing video!
kalki avatar (beast of the earth) (christ on the white horse) (son of man on clouds) is the biggest enemy of dajjal/antichrist/kali 😏
Kalki Avatar (Murtaza) cousin of Moula mahdhi a.s. (muhammad) 😎
Moula mahdhi is raja shashidhuvj 😎
Prophet Moula mahdhi and Moula Isa both will kill dajjal cause dajjal is going to kill Kalki Avatar 😏
Kalki Avatar will follow orders from 2 religious king Moula mahdhi a.s. and Moula Isa a.s. 😎
Kalki Avatar going to have 2 swords and ring of moula sulaiman a.s. and staff of moula musa a.s. (iron rod) Staff of moula musa a.s. is like omintrix can transform into anything and can transform others into anything And stone in the ring of moula sulaiman a.s. is also known as kastav mani and it's more powerful the all 6 infinite stones combined 😇
This staff will transforms into white horses with wings,weapons,iron-man,cloud etc or can do imagination into reality 😎
*Ratn sru sword of lord shiva (miri)😇
*Ratn varu (zulfakar) sword of Moula Ali (piri) 😇
miri piri 😇
Satyug (sunrise from West) 01.aug.38 😏
Gzwa e hind 2029 😎....
EE student here. Very well explained! If only we received teaching on this level in class.
Thanks Garrett! I really appreciate that feedback, gives me a little pick-me-up for the day :-)
when i was in university i didn't have youtube, i didn't even have the time to open my computer
@@goldenbeardofficial8541 so what was you doing? 😂
I wish my professors I had through college explained things like this with this level of focus and clarity, thank you for the very informative video
I'm an EE student and i gotta say my teachers really explain just because they need a paycheck. And at a stage i was like: damnnnn EE is boring but this channel totally proves me the otherwise. I just found it last night and i'm fascinated. Great job !!
Haha! That's awesome to hear! Yeah, EE can be boring in the wrong hands but I think we're fortunate that all of the engineers here at CircuitBread find it fascinating, which helps keep us motivated when things are challenging.
Great soothing voice. I want this guy to read to me at night before I go to sleep.
"And then the cathodes and the anodes lived happily ever after."
That was so clear and helpful, not only for EEs but also for beginners and hobbyists.
Thank you 🙏
Glad it was helpful!
I agree, This gives a much better visual and simplified explanation to match what the textbook is describing
Well I had to watch a 101 version about diodes but then I came back and this made a lot more sense.
This was such a helpful and in-depth explanation of how LED's work, thank you!
This channel actually makes EE look interesting... Thank you for your hard work!
Very nice and easy way to explain led . great job
This is explained so well…I could cry
You could say a regular diode produces heat by emitting infrared. LEDs just have a different omposition which causes then to emit radiation with a smaller wavelength, e.g., visible light.
Yep! Exactly. Though the LEDs still emit a little bit of heat as well, just less than a regular diode.
You sir are the best electronics teacher I have seen. Better than my professor. I will gladly subscribe to your channel. Keep it up!
Wow they really are just crazy simple. Simpler even than other light bulb designs.
Thank you very much for the excellent explanation.
I have never been lost faster in a how-to video. I appreciate your credibility, but you might want to do another that explains what diodes are as well.
Hi there! We actually have several videos on diodes - a higher level video on how they work as well as several videos on how they work at the semiconductor level. Hopefully they clarify things!
This was extremely helpful. Thank you very much!
❤Love this channel. Appreciate the good work.
Thank you so much for your feedback! Glad we can help!
Thank you for sharing such valuable knowledge!
thankyou sooo much sir i was just done with my chapter semiconductors in 12th and i didn't get how the transmits,,,,,,, brilliant explaination
Since we touched this but didnt get tested on this (Eng student, but not EE), im happy with how it was covered
You did't study that in high scoohl
Super concise! Thanks :)
Wow! That's everything i wanted to know!
Awesome, that's good to hear!
please make a video explaining how CFL light bulbs work...
perfectly explained.
It's interesting to read the comments from students regarding the good teaching styles on these types of videos. I've learned more on UA-cam from channels like this than I could have ever learned in school, where most Teachers (in my experience) quite obviously couldn't be bothered.
Teachers can be hit or miss, unfortunately. But there are great teachers out there that do really care about students, you just have to find them. And hope they're not burned out by being overwhelmed by students who yearn for help. One of the greatest professors I had as an undergraduate went above and beyond and, even ten years after I got my bachelors, was willing to help us with a handful of these semiconductor devices videos, making sure they're accurate. Those are the type of teachers and professors I'm grateful for.
@@CircuitBread Indeed, however, mostly 'miss' in my experience.
Very well explained ..... Wish college was like this
Thank you! We're actually hoping, once we get more content up, to actively partner with colleges on some content so that students can have their in-class and our video/written tutorials work together. I don't know how well it will work out but that's something we're striving for.
Thank you
Thanks! It's really helpful!!!
Well explained....
Well explaination dear sir 👌
But yet i have not got that why LED's design is of that type could you give me some more explaination ???
Why LEDs look the way they do with the dome? I think it's just a manufacturing standard developed years ago that was easy to make and didn't block any of the light coming from the light emitting portion itself. There are many, many different body styles now available.
@@CircuitBread thank you 🙏
Very well made video. EE student here
Do you have a video about the transitory evolution and hot logic gates made computing possibly?
Interestingly enough, we have shot a video about how a computer works from the ground up - starting with sand and talking about how that's turned into semiconductors which are then turned into logic gates, etc. While the video is completely shot, there are a few animated portions of it that are being time consuming. I'm not sure if this is exactly what you're looking for but we're quite excited for this video to be published. Whenever it actually happens...
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors.
ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
wow, the color is determined by the phonon! ive never thoght about it now well understood. great lecture!
I know, it kinda blew my mind when I learned about this as well. Thanks for the feedback!
I think it would be more accurate to say the energy from electrons falling into holes in a rectifier diode are released as infrared photons. It becomes heat because most rectifier diodes have opaque black bodies.
You are absolutely correct, thank you!
Super.....:) Keep this good work ..Thanks again
Can someone please explain how energy is conserved when the photon is emitted? The valence electron passes from the n region to p region as a result of the voltage across the two regions supplied by the power supply-energy is conserved by producing a current (which is literally that transfer of the electron), makes sense. But when that valence electron emits the photon where does THAT energy come from? Is it being coming from the momentum of the electron as it is brought into orbit of an atom in the p region? Please explain... I cannot figure that part out. Amazing video!
You're right - it's when the electron goes into orbit of an atom in the p region, dropping in its orbital energy to do so. We say it "fills a hole" but the reality is that it's just dropping into the valence band, or, in other words, being pulled into orbit around a specific atom. The energy it loses from dropping into that hole is emitted as a photon, producing the light.
Now, where I'm a bit sketchy and would rather have someone with a PhD or just better specialization in this field confirm, is that the electron *does* lose energy crossing the junction and getting onto the p-side, but then the electron loses *more* energy when it drops into orbit of the atom. I'll leave this out there if someone (including other engineers at CircuitBread) want to comment. Excellent question, thank you!
@@CircuitBread Thanks for the detailed response! That really clears things up for me. I do know that energy is conserved when the electron moves position as a result of the chain of electrons in the circuit simultaneously moving (that is, a current through the circuit) which takes energy from the battery. Think of a watering hose, if it is full of water (wire full of electrons) and you add some more water to it via a water supply (adding electrons to the wire with a CV source), water is immediately spilled out on the other end, thus the energy gained from forcing water into one end is conserved when water is spilled out the other end. Same concept with electron flow. With this in mind, I do not think that it is the individual electron loosing energy as it crosses into the p region, instead energy from that action is consumed in the battery as a new electron further down the line enters a charged terminal as another electron leaves the terminal of opposite charge.
@@greenief9097 can you please explain how electron energy is lowered when it goes to orbit around atom
Since when electron is confined to move within an orbit it's Δ x is less, so Δ p should be more acc to uncertainty principle
@@CircuitBread can you please explain how electron energy is lowered when it goes to orbit around atom
Since when electron is confined to move within an orbit it's Δ x is less, so Δ p should be more acc to uncertainty principle
@@pavanjoshi2448 Having taken a course on it since the time of my first reply, look into "potential energy wells." Specifically finite potential wells. It is a pretty abstract idea, and connects the wavelength of the electron to the energy it has.
When the electron is passing from one atom to the next, it briefly inhabits free space. Think of a ball that has rolled down a hill and is resting at the bottom. But then, it comes within the vicinity of the next atom, and this is similar to saying that the ball now is near a ridge where it can fall down. As the electron falls into orbit, loosing the potential energy it had and gaining kinetic energy, it emits a photon of a specific wavelength to compensate for the energy change.
This is not an in depth answer: look into potential wells!
Thanks bro you came in clutch my project is due today
👍Awesome!
It helped me for my class 12 exams 😁
I'm in healthcare and even I understood this. Incredible video!
Awesome!!
I have a question.. is there a material of LED that can produce all wavelength? I mean, we just modification of voltage or something else to make different wavelength?
Not that I'm aware of - unless I've missed some update in some basic physics (and I'm not saying that sarcastically, there are constant updates in the scientific fields) then the wavelength of the emitted light is directly tied to the materials used in the LED.
At around 1:35ish, you discuss how for silicon diode, energy is released in the form of heat, whereas for led materials, the energy is released in the form of light. How come the difference in why one releases light and one releases heat ?
Thanks
Yeah! It's all about the wavelength of the energy and how much of a drop in energy there is when the electron changes from one energy level to the other. This is actually how they have made LEDs of different colors - blue, a higher energy light, requires a greater energy drop of the electron than red light so they put together two materials where there is the appropriate change in energy level from one to the other. So, there are a few things going on here but if the electron drops a smaller step, like in a diode, the energy is in the infrared range and is trapped inside the device itself - heat!
@@CircuitBread Ahhh I see, interesting. Appreciate the reply. Great video btw.
Really good explanation here, I'm just your typical inattentive ADHD fella who can't turn off his brain and this has definitely been helpful!
@2:30 - 2:50 Was it Maxwell that figured out the wave lengths to produce ultraviolet light?
He predicted the existence of electromagnetic waves but I'm not sure who it was that actually figured out which wave lengths produce ultraviolet light...
Maybe this is a dumb questions but how do the holes get replenished? It seems like they disappear when recombined but the LED doesn't really "run out" right?
No, not a dumb question at all, it's something I think all of us have considered at one point or another. My understanding is that it's just a matter of it being a true circuit - as the holes are filled with the electrons dropping into them, holes are forming elsewhere due to the energy being put into the system. The holes slowly move into place and replenish the lost holes. Since it's done constantly, there's never a real lack of holes. I need to reach out to my semiconductors expert again, she may have a more technically fulfilling way of describing it.
Very well explained ... Thank you.....
You're welcome, thanks for the feedback!
In regular diodes electrons radiate IR light, but in LEDs they radiate electromagnetic waves in visible region
Very helpful 👍
Dear sir,
thanks for your explanation. I have one question on energy conservation in photo-diode.
In case of LEDs, the battery is injecting high energetic electrons (from its negative terminal) to the conduction band at n- side and collecting low energetic electrons (by the positive terminal) from the valence band at p-side. So the battery is losing energy which is manifested as light(or heat).
Can you please explain (by using electron/hole movement) how energy conservation is valid in photo-diode/photo detectors.
In this case, when i am drawing the schematic diagram of electron-hole movement, it seems to me that the battery is getting the absorbed photon energy (I mean battery is getting high energy electron from the conduction band at n-side and releasing low energy electron at the valence band of p-side). How is it possible? How the battery can store the absorbed photon energy? I am doing something wrong.
I disagree, you aren't doing anything wrong - the battery WILL absorb the photon energy. A photo diode is, in essence, just a small solar cell. Depending on the setup, the current generated by the photodiode may go back into the battery or it may go elsewhere in the circuit. If the battery is non-rechargeable, hopefully it won't be going back into the battery but, at the same time, the amount of current these small photo diodes create are extremely small and probably non-problematic.
Thank you very much
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors.
ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
@@CircuitBread
I'm not trying to take away from your lecture, I thought it was great.
New sub
That was cool! I never knew how closely related LED's and transistors were. It seems the difference is the extra doping of the P/N in the transistor?
It is pretty crazy technology! It's not the amount of doping, it's by putting two different materials together that, when an electron moves from one to the other, it loses the exact amount of energy needed to create a photon of the color you want. Most diodes just produce heat when the electron loses that energy.
What happens when all the electrons cross and fill all the holes? what reiterates the process? Thanks (I have no idea how these things work but I find it very interesting)
I think they get filled by the power source ie; Battery or outlet.
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors.
ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
Thank you!!! I can now win that argument between me and my cousin lmao
Yes! This brings me a ridiculous amount of joy. I hope it was fun!
this only confirms my thoughts, though vaguely... i want to believe the electron is being stripped into photons but since i myself am not an electron, i cannot actually see the process
nah, electrons can't be destroyed with this ease
Thanks, I've explained to my son.
Forgot some of my Physics degree.
Thanks man!
this is amazing!
I always retain a little hope that someday I will see the toast pop out again.
3:15 I didn't understand why the lead frame shaped like this(like triangular plane)? Why not designed it like a column that holds the semiconductor material
Hey Amjad, I don't know but I have a theory I think is reasonable. The light emitting side is the cathode, so you want as much available surface area there as possible. However, a thin vertical bar would be pretty weak mechanically. So, by creating those two odd shapes, you're maximizing the surface area on top of the cathode while still providing enough mechanical strength to both the anode and the cathode to not be bent during the encapsulation process. A flaw in this thinking is that the wire between the anode and cathode is tiny and doesn't seem to be affected. Hmmm... I hope someone else that knows the answer will chime in.
What if electrons occupy all the holes in p type region??? Will the diode stop emitting light then??
I had that same question when I first learned about this. My understanding is that once the electrons drop in energy, then they act like a "normal" electron in that material, which means they can later jump into the conduction band and be conducted out of the device to go around the circuit loop again.
Superb 🤗
CAN YOU TEACH KTU SYLLABUS 😀
THAT WILL BE HELPING MY JUNIOR'S 🙂
Sorry, what's a KTU syllabus? I'm getting "APJ Abdul Kalam Technological University" from a google search. We actually are trying to create our newer series to be more in line with general electronics syllabi but there's always going to be variations...
@@CircuitBread yaa its that itself 🙂
Thanks alot for the reply I never expected you would reply ❤️
Very well sir
2:55 So the next Nobel prize will go to someone who will discover material which emits all the colours depending on voltage.
That would be pretty amazing!
I don't think that is physically possible in a practical way.
Can someone please check my understanding of what is going on molecularly.
The voltage difference between the cathode and anode liberates a electron from the N type region of the diode. This electron finds a path to an empty positively charged hole in the P type region.
However due to the composition of the molecules around that hole, the energy loss for that electron to fill that hole will be of the same size as the desired frequency. It therefore sheds this energy in this form of photon to fill the hole it is drawn to.
A chemist or an expert in this field might take umbrage at the details or verbiage, but yes, that's a solid understanding of what's going on!
Many thanks for the response. Your videos are excellent and have been a massive help. 👍🏼
This video explains on a molecular level how electrons flow. It also breaks down the doping process of pnp/npn transistors.
ua-cam.com/video/J4oO7PT_nzQ/v-deo.html
Amazing vid!
What is an "electron hole". Why does the LED not stop working once all the "electron holes" are filled. This does not make any sense to me???
Yep, that was a question I had as well. What happens is that, since you have a voltage, those electrons drop into the holes on the other side of the PN junction and then those electrons (or, more likely, other electrons) eventually pop out of the holes again and work their way out of the semiconductor material to go around in a big cycle again. I recommend checking out our video on how a PN junction works to hopefully clarify this question.
The background tilt s making me nervous xD
just leaving a comment here hoping i will ever revisit this video for school
What is emitted at 2.2 - 2.5 volts?
I'm not sure, actually. My guess would be something yellowish-green.
How are knee voltage and energy gap related?
The larger the energy gap, the higher the knee voltage. You'll note this with LEDs of different colors. Different band gaps generate different colors, which is why LEDs of different colors have different band gaps. I'm not sure if there's a mathematical relationship between the two but I would be a little surprised if there isn't.
I like the video's style and how greatly articulated and visualized the explanations are. Much disappointed though, as I expected an explanation of how "white" is created in such a video instead of having it only listed along the LED's inherent colours in the video with no reference of its creation in the details or later on.
Sorry about that! In one of our RGB videos, it is mentioned that typically white is created by emitting a balance of all three colors. There is also a way of making a blue LED more white with some sort of coating but I'm not as familiar with that process as much. Creating white with the three colors is a lot more primitive yet widespread than you'd think.
Silicon diodes actually DO emit light, as proven by that one time I accidentally shorted a diode and it lit up like a Christmas tree.
It's just that the light produced by a diode is immediately blocked by the structure of the diode itself, which causes it to be absorbed.
I knew they emitted light, but I thought it was more in the red-infrared range. But yep, the opaque cover makes it so you can even see the little bit of light they do produce (under normal conditions). Thanks for sharing! It would've been cool to have gotten that on video.
I am wondering if LED lights emit the light a frequency so that your eyes percieve the light to less intense than the peak of each flash. Do LEDs flash on and off? Do you know if the human eye can detect this flashing? Does the brain then merge the flashes with the darkness inbetween and so percieve the light to be dimmer than the individual flashes but brighter than the darkness between these flashes?
LEDs, given a constant voltage, will give out a constant light. While the photons are discrete, there are so many of them, there is no way our brains could distinguish each one. On the other hand, a common way of dimming LEDs is exactly that method. They flicker the LEDs on and off fast enough that our brains can't register that they're flickering but instead interprets it as simply being dimmer. I have seen where they've flickered the LEDs too slowly and it gives a very subtle, nearly subconscious, strobing effect that is quite unpleasant.
@@CircuitBread damn, i hoped i was wrong. So you are agreeing, the led may appear less bright than it actually is, due to your brain merging the bright flash with the dark inbetween. I wonder if this means the retina or other sensitive parts of the eye may be more easily damaged by this LED light as the light is maybe brighter than the retina or optic nerve is percieving it.
I've wondered about that myself - it seems like if the flash were bright enough, even if the duration is incredibly short, then it would cause some damage.
Impressive
Lol I was wondering this sense we where talking briefly about light bulbs in science class
is it kind of the opposite of a solar cell?
Exactly! The LED is optimized to create light from power and a solar cell is optimized to create power from light but practically, it's the same thing happening in reverse.
Cool, I was deducing the same thing too recently!
Wow nice video
Would it be possible to turn an led into a fuse
Not really... as they're not designed for that, they could burn out open or burn out closed, which means that they could make the situation even worse. There may be fuses that incorporate LEDs to indicate their status - I haven't heard of that but there's a lot of things that exist that I haven't heard of.
Now I can build a photon cannon.
How does LED COB work?
Same exact concept but instead of the cup portion shown in this video, the yellow portion acts the same as that cup, emitting the light.
Thank you.
I actually have a new LED lamp into my bedroom.
I got scared when at light little light at night lightens and closes.
Is this normal ?
I'm sorry, I don't really understand, could you rephrase what the LED lamp is doing?
@@CircuitBread my new lamp
At night I close it
When I look at it on the roof it's off course
I see a little light like a small dot
After some time it finishes
I got scared
Hm, interesting. Strangely, LEDs are so efficient that they can emit a very small glow with small amounts of residual charge or stray voltage. While this can cause a glow to last a ridiculously long time (minutes), it is common for LED bulbs to take several seconds to wind down to a level that you can no longer see them.
@@CircuitBread
Thank you very much indeed for your valuable explanation.
This explained for me the issue
Grateful.
@@CircuitBread sir,
Do you have a face book page?
So I olrady thaugt the led light is the emotion of the energy transition that becomes light.
Light in the operside direction is a old trade light😍
The subatomic space dragg is less negative for it to expand in to for us to see light.
😍 than we are the ones losing photons 😍🤣😭😍
Breeee nice
This conformation.
👀 bit than man don't see the difference between photons en cosmic behaviure jad😅🌈
No mention of how LEDs work as the reverse of the photovoltaic effect? In the photovoltaic effect, an electron is freed from a low energy state by absorbing a photon; LEDs work by releasing an photon by an electron falling into a low energy state.
We discussed it but we ended up deleting that from the script because we didn't think we could do it justice without getting too deep into the physics behind it. We could've been wrong about that assumption.
Thanks 🙏🙇 a lot buddy
Our pleasure!
I think you have practically experience that grate
So is the light emitted unpolarized light (I hope it is; polarized light is bad for health, I've heard).
Also, do you know of any lead and arsenic-free LEDs? I've been looking all over the web...
These simple ones don't, but do many of the lights marketed as LEDs emit any UV?
I just had to ditch the idea of lighting my future home with Sodium Vapour Lamps because they contain mercury... Bioluminescent lights haven't evolved much yet...
If only there was a lead-and-arsenic-free LED...
LEDs emit unpolarized light but most all of them contain trace amounts of lead and arsenic. The quantities of these materials are extremely small, though, and while not ideal, is generally much more environmentally and biologically friendly than many other options. That is assuming you're using high-quality LEDs from a reputable source - some LED manufacturers may be less focused on following environmental regulations.
In regards to UV, unless the LEDs are specifically designed to emit UV, their emissions in that spectrum are minimal to non-existent. That's one reason they're popular as outdoor lights - their limited heat and UV output makes it so they don't attract bugs like incandescent bulbs do.
@@CircuitBread Thank you so much; your reply gave me much relief... I was so worried... Not anymore though. Bullish on LEDs now; YOLO!
How do LEDs that change colours work?
Hey Ben, we got a tutorial about that, go check it out here: www.circuitbread.com/tutorials/how-rgb-leds-work-and-how-to-control-color
@@CircuitBread thank you very much!
Combine RGB and increase or decrease intensity of either of those bulbs
But I think future science teaching will give stress on its practical side instead of teaching those electon proton theories. Where gallium is found and how it is placed in a LED knowing that is more important
I think that these fields will become more stratified and specialized. I think there will always be people who need to know the electron/photon theories so they can improve the underlying technology, while others will be focused on sourcing and purifying materials and fabrication methods. Just like Arduino has made it so that many people can jump right into embedded systems with limited electronics understanding but we still need the people who create the Atmega processors the Arduino is built on, as well as the library the IDE is built on.
Awesome video, very informational and concise!
edit: removed dumbass comment about symbols being flipped. lmao.
Thanks for the feedback! Could you let me know exactly which symbols were flipped? I only see three in the reference table and I *think* they're right. I appreciate you keeping us honest!
@@CircuitBread oh my lord i'm an idiot, hahaha. nevermind!
The more of these videos you watch, the more you will believe me when I say, "No worries, I do that sort of stuff ALL THE TIME." 😂
Sadly, the inventor of LED and semiconductor laser didn’t win Nobel Prize. 😢
That's mind blowing! 😮
💯💯💯
i thought i destroyed several L.E.Ds but, i stopped and tested the L.E.Ds that was left over and discovered that i was sent a bunch of bad L.E.Ds
Dang, that sucks. Good thing you tested them!
@@CircuitBread I bought some more but, from a different vendor... And they worked great 😃
A kind of crude scintillation.
Well ya lost me
💗
how does an led work?
👽
are leds bad for your eyes?
I've heard this concern and have even read a research paper about it that seemed inconclusive. I'm not a biologist or a doctor, so I can't say anything definitive on the physiological side. But, from an engineering point of view, I haven't come across anything that would make the think that LED technology is inherently worse for the eyes.
low volume
Wt converts into photons and photons r made of Wt 😒 ???
Just electrons or combination of electrons protons and neutron in a molecular structure of a photons 😑 ???
Not 100% sure I understand the question but if you remember that photons are just little packets of energy, not actual matter, that should help. So, instead of emitting energy as heat, it's emitting it as light.
@@CircuitBread
All photons or 99.99% of photons don't have light 😏
@@CircuitBread
It looks like photons r made of electrons and protons and have electrical and magnetic effect inside a magnatic sphere 😇
kalki avatar (beast of the earth) (christ on the white horse) (son of man on clouds) is the biggest enemy of dajjal/antichrist/kali 😏
Kalki Avatar (Murtaza) cousin of Moula mahdhi a.s. (muhammad) 😎
Moula mahdhi is raja shashidhuvj 😎
Prophet Moula mahdhi and Moula Isa both will kill dajjal cause dajjal is going to kill Kalki Avatar 😏
Kalki Avatar will follow orders from 2 religious king Moula mahdhi a.s. and Moula Isa a.s. 😎
Kalki Avatar going to have 2 swords and ring of moula sulaiman a.s. and staff of moula musa a.s. (iron rod) Staff of moula musa a.s. is like omintrix can transform into anything and can transform others into anything And stone in the ring of moula sulaiman a.s. is also known as kastav mani and it's more powerful the all 6 infinite stones combined 😇
This staff will transforms into white horses with wings,weapons,iron-man,cloud etc or can do imagination into reality 😎
*Ratn sru sword of lord shiva (miri)😇
*Ratn varu (zulfakar) sword of Moula Ali (piri) 😇
miri piri 😇
Satyug (sunrise from West) 01.aug.38 😏
Gzwa e hind 2029 😎....
Wut?