Used to watch these videos when I was a high school dropout and had a dream to study physics. Since I watched all of your videos, I have gotten my GED, done 2 years at a community college, and now am a Physics Major at University of Maryland working in a high powered laser optics lab. These videos started it all. I would watch them while at work and take notes on little sticky notes, which are still on the wall in my room. Thank you DrPhysicsA, seriously. You changed the entire trajectory of my life.
I had small particles and figments of knowledge from my teachers, but after watching this and taking notes, they've all combined to make a large mass of consolidated information. Thank you, my good Sir.
Hello. Can I say that I have really enjoyed watching this video and other videos of yours. I have been able to gain lots of information, in terms of my studies at both GCSE and A Level Physics, which the A Level Physics I'm doing distance learning. I'm also doing A Level Maths and A Level Further Maths, distance learning also. If it wasn't for people like you, who give up their free time to produce videos on such a good scale, I would be in a worse place. Can I say thank you very much for your help and support, it's appreciated very much. Regards Dominic G
V and r (internal) are constant. R (load) is variable. I = V/(R+r). Power thro Load = I^2 R = V^2 R/ (R+r)^2 = V^2/ R + r^2/R + 2r. Now for the power to be a maximum, the denominator must be a minimum. Diff w.r.t R and set equal to zero. You get 0 = 1 - r^2/R^2. So r^2 = R^2. So r=R.
Thanks for kind comments. My videos are an amalgamation of AQA, OCR, Edexcel and Cambridge A level syllabus for both AS and A level (with the exception that I don't tend to do the biophysics parts). The videos in the A level revision playlist "Atomic Structure - A Level Physics" contains atomic energy levels and photon emission when electrons fall down to lower energy levels.
Yes indeed. I can't now remember why I plotted it that way round. I suspect I was simply trying to show that there is a direct proportionality between current and voltage. But as you say, the slope of the graph which I drew is 1/R not R itself.
EMF is voltage. So it is electric potential (V) - potential energy per unit charge. Electric Potential Energy (Ep) is work done moving a charge (q2) from infinity to a point r away from q1. The Electric Field (E) is the Force per unit charge.
Well there is a quantum mechanical underpinning to all this, but for purposes of A level all I meant was that as the current passes thro the filament of the lamp it heats the filament (and thus produces the light). As the filament heats up, its resistance increases so the current falls. R increases because the electrons in the wire get more excited and therefore there are more collisions and interactions between electrons which impedes current flow.
Thanks so much, with only a couple of weeks till my exam I wasn't sure if I could pass them, after watching your videos everything seems much clearer :)
Took physics in university a decade ago. Our professor stinks at really teaching us anything. Didn't understand a damn thing and its a miracle I managed to pass the courses. Anyway, I'm currently settled in my career unrelated to physics...but out of sheer intellectual curiosity decided to re-learn physics. I find your youtube channel highly valuable --"subbed." I am sure my life/career choices may have ended up differently had I actually understood this stuff a decade ago.
Unless I've missed a point, the answer is that you need about 0.7v across the LED before any current will flow in the circuit. So for the first 0 - 0.7v I would expect no current. Thereafter, assuming there is a resistance in the circuit I would expect current to grow proportionately with voltage.
N is number of charge carriers passing a given point per second. Q is the total charge passing a given point per second. But charge flowing per second is current. I=Q/t
You're a life saver. Your videos saved me like 50-60 pages of reading. Your explanations are thorough yet simple to follow and idk you just made my life THAT much easier.
To help better my understanding of how electricity works, I envisioned myself being an electron whizzing around an electron which constantly reversed EPE as I deliver energy to different electrical components and release energy as light quanta.
Thank you so much. I have always had a problem with grasping the abstract essences of electricity. Your profound video has helped healed my wound and made me get it. Thanking you a thousand times would still not repay what you have done to the world.
Electricity which flows through miles of power cables suspended from pylons is still subject to a potential difference, otherwise no electricity would flow. Of course, for the most part the electricity is alternating current. Because the power cables are themselves part of the enormous circuit that is why it is essential to transmit at high voltage so as to minimise power losses through the cable.
It is "Atomic Physics 3: Semiconductors, Diodes and Transistors". But you might want to watch videos 1 and 2 first to set it all in context. You can find these on my home TH-cam page (drphysicsa) in the playlist Atomic Physics. Thanks for kind comments.
I think it was Benjamin Franklin who started the idea of electricity flowing from + to -. You will recall that electricity was used long before it could be explained quantum mechanically and before electrons had been discovered. It was therefore just unfortunate that current flow was determined to be the opposite direction to the particles which actually flow - ie the electrons.
At 3:56, the point I'm trying to convey is that N if the total number of electrons flowing per second, Q is the total charge flowing per second and that that must therefore represent the current I.
Yes indeed. You will find a set of vids on QM in my Quantum Mechanics playlist (see main page of my TH-cam channel) and you will find additional Waves vids in the playlist on A Level Physics.
i am so confused. Why do you sometimes use the direction of conventional current and sometimes you use the "actual"direction.?? What should we assume in the exam?? Thank You!!!
The problem arises because electricity was discovered before anyone knew anything about electrons. It was assumed that electricity travelled from positive to negative and that is what we still call the conventional current. But we now know that the electricity is the flow of electrons which actually travel from negative to positive because they are negatively charged and are therefore attracted to the positive terminal. We retain the idea of a conventional current travelling from plus and minus even though nothing actually flows in that direction.
DrPhysicsA "historical reasons" i thought the the whole selling point of science was that it was willing to change ideas based on evidence. Physics has failed. Archimedes rolls in his grave.
at 16:20 shouldn't it be -I3R3 + I2R2? since if we're going with the current direction, there must be a voltage drop and if we're going against the current direction then it will be a voltage gain?
Great stuff - one thing to correct you on, however. In the derivation of I = nAve, you say that n is the 'number of electrons per m^3'. Actually, it's the number of 'free electrons per m^3'; most of the electrons can't carry a current, as they're bound into the shells of the atoms, and it is only those which have been 'delocalised' that can carry a current. A small point, but one that I have seen marks for in mark schemes (WJEC in particular, who love it).
double circuit confuses, why it is zeo when you go baxk to where you started>>? I think until the loop is closed it should be continuing without break and voltage cannot be 0 because current continues to flow until it won' slow it down to the stop. I might be wrong but yet I don't understand why you substract the current from total energy??
Taylor Shill potential difference across a parallel circuit is the same across each branch in every scenario. This means that, the same electromotive force is doing work on these charges, and if there are resistors, the current will be distributed through each equal to the ratio of the resistances. That is to say, the same force is pushing the electrons, so less go through high resistances and more pass through the lower resistances. If you have a parallel circuit with a battery with internal resistance, you can first find the total external resistance using the reciprocal addition of resistances rule, and then treat that as a single resistance in series with the source of emf. The difference is, in a parallel circuit the voltage is the same across the whole and in a series circuit it’s the current that’s always the same. This means that, in a series circuit the voltage has to be greater at higher value resistances in order to push electrons through and maintain the constant current. In this way, whilst in parallel the ratio of currents are equal to that of the resistances, in a series circuits it’s the ratio of voltages that’s in the ratio of the resistances.
considering Kirchhoff s 2nd law , what if there is a circuit with no appliance(no resistance) and only a cell connected , so as current flows through cell it would gain energy and this energy will add up when it completes one complete circuit and passes through cell for the second time, so current would keep on gaining voltage ? how is Kirchhoff law applied here
I got a little confused in the beginning when you talked about v being both a velocity and a distance. Wouldn't it be more accurate to talk about v as the velocity and vdt as the distance? In which case dN = nAvdt. Oh, and great series of physics videos. I got here via your mechanics videos. What you have made is very much appreciated :)
3:40 It is a bit confusing that 'v' denotes distance in 'Q=Avnq/sec' and velocity in 'I=Avnq'. 'Q' usually denotes charge (not charge per second) and 'v' usually denotes velocity, not distance. Hence, perhaps the first equation should rather be 'Q=Avnq·sec', or am I wrong?
might not be fair since ive already covered the first 3 topics of a level physics the past 2 weeks, but imma challenge myself to cover the remaining of the a level physics syllabus in 2 more weeks, and do past years for the next 2 to prepare for my trials. wish me luck!
0:36 The direction of current in the source and in the circuit is different! From "minus" to "plus" in the source and from "plus" to "minus" in the circuit. It's because the electrons flow in the circuit is not free, but driven by the source. The circuit also must be closed otherwise there'll be no current. It's written in books about historical convention, but it's purely practical as you can see. Means that everytime you see a drawing of a current in a book it is a part of the circuit not the source, if nothing else is specified. Many people are confused about it. I wonder if it was so hard to put in books this simple explanation instead of "historical convention" just to make it clear from the bigining?
Usually we plot a graph of resistance against 1/current. But if we invert the axis to 1/current on y axis against resistance. How do we display this in the form of y=mx+c?
***** Well we have the equation V=e-Ir so we rearrange this equation to make it appropriate for y=mx+c V=-rI+e so if you graph this you can look at the y-intercept for the e.m.f and take the absolute value of -r (|-r|) for the internal resistance.
e= IR +Ir divide by current e/I=R+r divide by emf 1/I=R/e+r/e Gradient is 1/e Y intercept is r/e Im assuming you mean the equation of the line on the graph of 1/current against resistance
do be careful not to confuse E for energy with epsilon for EMF. Also rho for resistivity should be lower case with a long tail and power should be a capital P.
My teacher tells me that the higher the voltage, the larger the current but if I=P/V , the higher the voltage, the smaller the current , can u help me plz~~
You should be using ohms law V=IR. for any given resistance R, then as you increase the voltage you will increase the current. You have used the power equation P=IV. It is certainly true that if you increase the voltage then in order to get the same power you can have a reduced current but that is not the same thing.
me too thinkkingg about learning the maths side of physics, but it is very intimidating for some one learning just out of general interest on how the universe works, but i seem to be moving more towards it, from morgan freeman docos on the universe/ quantum world, to more of these types of videos and sixty symbols, i will be watching you O.O... even while you sleep... (because of time difference :P)
Used to watch these videos when I was a high school dropout and had a dream to study physics. Since I watched all of your videos, I have gotten my GED, done 2 years at a community college, and now am a Physics Major at University of Maryland working in a high powered laser optics lab. These videos started it all. I would watch them while at work and take notes on little sticky notes, which are still on the wall in my room. Thank you DrPhysicsA, seriously. You changed the entire trajectory of my life.
My procrastination has lead to last minute panic revision.... once again.
I am glad there is someone in the same boat as me!
Oh I'm 100% sure its not just us two either I can name at least 50 from my college alone :P
Lol, I'm watching this video a few hours before the exam. I am the one who's ACTUALLY doing last minute revision.
loool Aditya Chaturvedi ikr me too
Same here. But i have 10 hours i also need to sleep at some point...
You are a credit to the internet.
I had small particles and figments of knowledge from my teachers, but after watching this and taking notes, they've all combined to make a large mass of consolidated information. Thank you, my good Sir.
Hello.
Can I say that I have really enjoyed watching this video and other videos of yours. I have been able to gain lots of information, in terms of my studies at both GCSE and A Level Physics, which the A Level Physics I'm doing distance learning. I'm also doing A Level Maths and A Level Further Maths, distance learning also. If it wasn't for people like you, who give up their free time to produce videos on such a good scale, I would be in a worse place. Can I say thank you very much for your help and support, it's appreciated very much.
Regards
Dominic G
U completed education? Now u do research?
@@mathematicsfanatic832 he's a crack dealer
@@homunculus3646 Guys keep it civil please
your mum works at the crack den. She's a lieutenant
V and r (internal) are constant. R (load) is variable. I = V/(R+r). Power thro Load = I^2 R = V^2 R/ (R+r)^2 = V^2/ R + r^2/R + 2r. Now for the power to be a maximum, the denominator must be a minimum. Diff w.r.t R and set equal to zero. You get 0 = 1 - r^2/R^2. So r^2 = R^2. So r=R.
Thanks for kind comments. My videos are an amalgamation of AQA, OCR, Edexcel and Cambridge A level syllabus for both AS and A level (with the exception that I don't tend to do the biophysics parts). The videos in the A level revision playlist "Atomic Structure - A Level Physics" contains atomic energy levels and photon emission when electrons fall down to lower energy levels.
One day challenge - learn 2 years of A level physics in 1 DAY! *LET'S GO* -im gonna fail-
Silent Pixel did u pass?
Dinesh Raj I'd say I failed ;-;
i'd be the next one! 1 day before the exam!!!!!!!!!
1 day challenge is back!
24:18 challenge is backkkkk
Didn't know Bruce Forsyth could do Physics... ;-)
5 years after graduating college, i now know what I want(ed) to major in: physics.
Yes indeed. I can't now remember why I plotted it that way round. I suspect I was simply trying to show that there is a direct proportionality between current and voltage. But as you say, the slope of the graph which I drew is 1/R not R itself.
Outstanding. Every physics class I took (3) presented 1/R = 1/r1+1/r2+1/r3 as axiomatic. I've never seen this (simple) derivation before. Thank you.
I Reff = I R1 + I R2 + I R3
I Reff = I (R1 + R2 + R3)
Divide both sides by I
Reff = R1 + R2 + R3
Similar approach with the parallel circuit
EMF is voltage. So it is electric potential (V) - potential energy per unit charge. Electric Potential Energy (Ep) is work done moving a charge (q2) from infinity to a point r away from q1. The Electric Field (E) is the Force per unit charge.
One of the best videos explaining this concept.
I haven't got great physics teachers and electricity if not taught right is hard to understand, and this is really helpful! Thanks a lot!
Well there is a quantum mechanical underpinning to all this, but for purposes of A level all I meant was that as the current passes thro the filament of the lamp it heats the filament (and thus produces the light). As the filament heats up, its resistance increases so the current falls. R increases because the electrons in the wire get more excited and therefore there are more collisions and interactions between electrons which impedes current flow.
Thanks so much, with only a couple of weeks till my exam I wasn't sure if I could pass them, after watching your videos everything seems much clearer :)
Took physics in university a decade ago. Our professor stinks at really teaching us anything. Didn't understand a damn thing and its a miracle I managed to pass the courses. Anyway, I'm currently settled in my career unrelated to physics...but out of sheer intellectual curiosity decided to re-learn physics. I find your youtube channel highly valuable --"subbed." I am sure my life/career choices may have ended up differently had I actually understood this stuff a decade ago.
Thanks.. You just gave me a reason why i need to learn this.. Haha
Unless I've missed a point, the answer is that you need about 0.7v across the LED before any current will flow in the circuit. So for the first 0 - 0.7v I would expect no current. Thereafter, assuming there is a resistance in the circuit I would expect current to grow proportionately with voltage.
N is number of charge carriers passing a given point per second. Q is the total charge passing a given point per second. But charge flowing per second is current. I=Q/t
You're a life saver. Your videos saved me like 50-60 pages of reading. Your explanations are thorough yet simple to follow and idk you just made my life THAT much easier.
Brill lecture doc. You need to set up a patreon account
honestly we must do smthing to convince him to start again, when I'm bored I always watch his videos
To help better my understanding of how electricity works, I envisioned myself being an electron whizzing around an electron which constantly reversed EPE as I deliver energy to different electrical components and release energy as light quanta.
How long is your paper?
SmoothPinnacle Its A3 size
Because you put it in a circuit to measure current. If it had a sizable resistance it would reduce the current in the circuit.
Thank you so much. I have always had a problem with grasping the abstract essences of electricity. Your profound video has helped healed my wound and made me get it. Thanking you a thousand times would still not repay what you have done to the world.
Electricity which flows through miles of power cables suspended from pylons is still subject to a potential difference, otherwise no electricity would flow. Of course, for the most part the electricity is alternating current. Because the power cables are themselves part of the enormous circuit that is why it is essential to transmit at high voltage so as to minimise power losses through the cable.
It is "Atomic Physics 3: Semiconductors, Diodes and Transistors". But you might want to watch videos 1 and 2 first to set it all in context. You can find these on my home TH-cam page (drphysicsa) in the playlist Atomic Physics. Thanks for kind comments.
I think it was Benjamin Franklin who started the idea of electricity flowing from + to -. You will recall that electricity was used long before it could be explained quantum mechanically and before electrons had been discovered. It was therefore just unfortunate that current flow was determined to be the opposite direction to the particles which actually flow - ie the electrons.
I can only learn stuff from highly formalized concise lectures otherwise it doesn't stick. Don't ask why. The good Doc's a Godsend. ;)
At 3:56, the point I'm trying to convey is that N if the total number of electrons flowing per second, Q is the total charge flowing per second and that that must therefore represent the current I.
Yes indeed. You will find a set of vids on QM in my Quantum Mechanics playlist (see main page of my TH-cam channel) and you will find additional Waves vids in the playlist on A Level Physics.
Thanks. Glad it was of some help. Good luck in any exams you may be taking.
I've spent weeks Trying to grasp electric theory.. This is a handy lecture
Which A level syllabus are you studying?
Its a quantum mechanical effect. See my 3 videos on Atomic Physics 1, 2 and 3.
Where did I do that?
Not that I am aware. And I was never much good at chemistry.
I finally understood where the 1/R+... and R+... formulas originate from, thank you!
Yes if you are making the point that the charge is negative.
thank you so much! my teacher didnt explain how to find I2 and I3 and i struggled a lot with it, but im so glad i found your video! :)
Not done that yet. I'll put it on the list.
R eff , a gcse concept explained so much more elegantly than my GCSE teachers!
I'm thanking you now, but hopefully we'll all come back here tomorrow and thank you more because the exam went well, thanks to you.
Thanks. I'm glad the first part helps. I hope that in due course the second part will make sense too.
i am so confused. Why do you sometimes use the direction of conventional current and sometimes you use the "actual"direction.?? What should we assume in the exam?? Thank You!!!
The problem arises because electricity was discovered before anyone knew anything about electrons. It was assumed that electricity travelled from positive to negative and that is what we still call the conventional current. But we now know that the electricity is the flow of electrons which actually travel from negative to positive because they are negatively charged and are therefore attracted to the positive terminal. We retain the idea of a conventional current travelling from plus and minus even though nothing actually flows in that direction.
so in the exam...
DrPhysicsA "historical reasons" i thought the the whole selling point of science was that it was willing to change ideas based on evidence. Physics has failed. Archimedes rolls in his grave.
Because I have assumed that I2 goes down the central limb. I2 will of course have elements of I1 in it.
Exam morning watching these videos,
That feeling of knowing everything i need
Sir? Did you know that you rock? THANK YOU for rocking!
Thanks. Good luck in the exam.
You have a voice of Gordon Ramsey when he cooks, except that you, you deliver knowledge about physics :D
+Deeya Bheeroo Gordon Who?
such a helpful and well explained vid thank you
sir, i like ur ., videos.
this brings students for more information about a level ..
thank you sir
Good luck.
at 16:20 shouldn't it be -I3R3 + I2R2? since if we're going with the current direction, there must be a voltage drop and if we're going against the current direction then it will be a voltage gain?
Mahmoud Matar yep
Ya something seemed off to me. So straight to the comments I went lol.
Me toooo
Hope it goes well. All good wishes.
I love those graphs that explain the mathematical process!
Your Videos are so frickin useful! thanks so much for helping us all through history A-level!
Thanks a lot for your videos, this are extremely helpful and I am truly grateful
These are a very valuable set of videos you've produced, great revision tool.
With your videos I understand it instantly, making my revision fun and productive. Thank you so much for posting these revision videos :) James Yr.12
Good luck in the exam.
so much better than my physics teacher THANK YOU!
Great stuff - one thing to correct you on, however. In the derivation of I = nAve, you say that n is the 'number of electrons per m^3'. Actually, it's the number of 'free electrons per m^3'; most of the electrons can't carry a current, as they're bound into the shells of the atoms, and it is only those which have been 'delocalised' that can carry a current. A small point, but one that I have seen marks for in mark schemes (WJEC in particular, who love it).
double circuit confuses, why it is zeo when you go baxk to where you started>>? I think until the loop is closed it should be continuing without break and voltage cannot be 0 because current continues to flow until it won' slow it down to the stop. I might be wrong but yet I don't understand why you substract the current from total energy??
I wish I could repay you for all the help!
Does Kirchhoff's Law apply if the resistor have different values? Does I3 + R3 - I2 + R2 = 0? If R is different values.
This is such a useful resource, thank you! You explain it so much better than my teacher did :)
I have a question, what happens to the potential difference in a parallel circuit containing branches with components of different resistances?
Taylor Shill potential difference across a parallel circuit is the same across each branch in every scenario. This means that, the same electromotive force is doing work on these charges, and if there are resistors, the current will be distributed through each equal to the ratio of the resistances. That is to say, the same force is pushing the electrons, so less go through high resistances and more pass through the lower resistances. If you have a parallel circuit with a battery with internal resistance, you can first find the total external resistance using the reciprocal addition of resistances rule, and then treat that as a single resistance in series with the source of emf. The difference is, in a parallel circuit the voltage is the same across the whole and in a series circuit it’s the current that’s always the same. This means that, in a series circuit the voltage has to be greater at higher value resistances in order to push electrons through and maintain the constant current. In this way, whilst in parallel the ratio of currents are equal to that of the resistances, in a series circuits it’s the ratio of voltages that’s in the ratio of the resistances.
samuel McDonagh I thought the current was the same in any point in series circuit due to Kirchhoff’s 1st Law?
Thank you Dr Physics. it help me just lilbit to understand Electricity
thanks for the amazing videos,Dr Bob eagle.
Thank you for this video! English isn't even my first language but everything was perfectly clear :)
At 1:49, there's a symbol that looks like a sideways ribbon that you said is current. What is that symbol called?
Thanks. Good luck tomorrow.
You are excellent teacher wow thnaks for a level videos!
considering Kirchhoff s 2nd law , what if there is a circuit with no appliance(no resistance) and only a cell connected , so as current flows through cell it would gain energy and this energy will add up when it completes one complete circuit and passes through cell for the second time, so current would keep on gaining voltage ? how is Kirchhoff law applied here
Millikan's oil drop expt. See my vid on Charge and Mass of an Electron - A Level Physics
I got a little confused in the beginning when you talked about v being both a velocity and a distance. Wouldn't it be more accurate to talk about v as the velocity and vdt as the distance?
In which case dN = nAvdt.
Oh, and great series of physics videos. I got here via your mechanics videos. What you have made is very much appreciated :)
Thanks. All I mean is that if the speed is v meters per second then in one second the distance travelled is v meters.
3:40 It is a bit confusing that 'v' denotes distance in 'Q=Avnq/sec' and velocity in 'I=Avnq'. 'Q' usually denotes charge (not charge per second) and 'v' usually denotes velocity, not distance. Hence, perhaps the first equation should rather be 'Q=Avnq·sec', or am I wrong?
wrong.....
adil m...?
Laureano Luna Understand the confusion. I was simply saying that in one second the velocity in metres per second represents the distance.
Brilliant video, thanks for this!
Great video, so helpful
might not be fair since ive already covered the first 3 topics of a level physics the past 2 weeks, but imma challenge myself to cover the remaining of the a level physics syllabus in 2 more weeks, and do past years for the next 2 to prepare for my trials. wish me luck!
0:25, are the electrons which are flowing originally from the copper atoms in the wire?
Amazing, thanks so much was really helpful
0:36 The direction of current in the source and in the circuit is different! From "minus" to "plus" in the source and from "plus" to "minus" in the circuit. It's because the electrons flow in the circuit is not free, but driven by the source. The circuit also must be closed otherwise there'll be no current. It's written in books about historical convention, but it's purely practical as you can see. Means that everytime you see a drawing of a current in a book it is a part of the circuit not the source, if nothing else is specified. Many people are confused about it. I wonder if it was so hard to put in books this simple explanation instead of "historical convention" just to make it clear from the bigining?
Thank you so much for doing all these videos, they're very useful :)
I need to read the textbook three times to understand the concepts and theory in any topics in the A level Physics syllabus.
If only my teachers could have explained it as simply as this. At least I watched it a week before the exam so I hopefully now won't fail xD
Really wonderful explanation
Very helpfull...but why did you stop uploading lectures???
In the exam (A level), should I use the + to - (conventional current) OR - to + ?
You use conventional current for the exam
Lauren Cutler Thanks!
How do i put this emf in form of y=mx+c?
Why do you want to do so?
Usually we plot a graph of resistance against 1/current. But if we invert the axis to 1/current on y axis against resistance. How do we display this in the form of y=mx+c?
***** Well we have the equation V=e-Ir so we rearrange this equation to make it appropriate for y=mx+c
V=-rI+e so if you graph this you can look at the y-intercept for the e.m.f and take the absolute value of -r (|-r|) for the internal resistance.
e= IR +Ir
divide by current e/I=R+r
divide by emf 1/I=R/e+r/e
Gradient is 1/e
Y intercept is r/e
Im assuming you mean the equation of the line on the graph of 1/current against resistance
***** Is PhysicsNet.co.uk your site?????
do be careful not to confuse E for energy with epsilon for EMF.
Also rho for resistivity should be lower case with a long tail and power should be a capital P.
Just letting people know it is not kirchoffs law its kirchoffs statement or rule because he never intended it to be a law and it can be broken
Actually, the professor who claims to break it is overlooking a few facts but oh well, I suppose energy can be created and destroyed
you are a great teacher
My teacher tells me that the higher the voltage, the larger the current but if I=P/V , the higher the voltage, the smaller the current , can u help me plz~~
You should be using ohms law V=IR. for any given resistance R, then as you increase the voltage you will increase the current. You have used the power equation P=IV. It is certainly true that if you increase the voltage then in order to get the same power you can have a reduced current but that is not the same thing.
Very nice and elaborative video... :D
me too thinkkingg about learning the maths side of physics, but it is very intimidating for some one learning just out of general interest on how the universe works, but i seem to be moving more towards it, from morgan freeman docos on the universe/ quantum world, to more of these types of videos and sixty symbols, i will be watching you O.O... even while you sleep... (because of time difference :P)
keep up the great work! this video helped me a lot