Mahesh sir, I survived 12th onnnnnly becz of youu. I am a person who cannot move to another topic without understanding it till the roots and this was pretty difficult for me since i found no perfect explaination to why things were the way they are. Ever since i got a hand on your videos, life has been great. I smile as wide as i can at the end of each video. And the satisfaction that i get on understanding a concept is enormous. And i owe that all to youhh! Thankyou so much for making 12th interestinggg....So much love from chennai❤❤❤❤❤❤
Same....without understanding one topic I don't even feel like reading other things Ur my senior Ig..but it's nice to see some ppl like me I really love these concepts... it's just really fascinating and I have respect for ppl who found all these theories and also the great teachers who actually put effort in making us understand... Thank you khan academy! Btw, I wrote this under this reply since I relate to this...don't misunderstand.
I just started watching and I didn't realize how time went so fast which is obviously good. There is a saying right, when we have fun the time flies quickly. Yes, indeed it was very interesting and fun to watch this. I don't usually have fun studying but this is a rare case.
I am an INOI student, but I didn't get a chance to qualified to IOI, so I have to do JEE this next year 2025 in order to get a better college or university, thank you sir for your wonderful explanation❤.
Pls tell explain I have some confusions: Electrons move in random directions without potential differnce(or electric field ) due to temperature , this is thermal velocity. as they move in random direction , the net current is zero.. simple Now electric field (constant which is same at every point is applied)this is unlike non unifrom field which decreases with distance since electric force/field is constant acceleration . Well let us consider a scenario where there are no ions to collide. An electron must move in unifrom accerlation from negative to positive terminal since it has no obstacles and veloctiy must increase unifromly let us consider Electic field is E charge e (only considering for one electron in just electric field alone so F=eE and a= F/m= eE/m right this is for one electron.. My questions are : 1. How do we visualise current in a conductor? 2. For example if we take a current of 1microA ok let's condier this it has about 6*10^12 electrons by definition of current these many electrons has to cross the conductor per second but am I wrong to visualise current as a single entity since electrons are spread everywhere in the conductor if drift veloctiy is about 10^-4m/s then how can huge amounts of current or electrons transfer and we get the current appliances working? Is it because of electric field or high speed thermal veloctiy? Moreover since we consider average veloctiy of electrons then current should also be Avergae since electrons move in different directions we are summing the vector vectorially but the actual directions differ also how the collision result in decelration to maintain same veloctiy how all these take place?even in a simple electric circuit how do we visualise this.. it's confusing I want to know these things
@achuthambi28 look, electrons in a conductor move in random direction, when no electric field is applied, but when Electric field or current is applied from the start of the conductor, electrons will try to move in an opposite direction to that of an electric field, since electrons is a negative charge, the electrons from the end of a conductor will hit some electron that is next to it with some acceleration, and vice versa, it's like tranfer of energy from electron to the other, untill the electrons hit the start where current is applied, actually current is the electrons that are drifted from the end of the conductor towards the start. That's all I know brother
@achuthambi28 if we applied strong current, then they will move more faster, and also depend on conductor, but I don't yet why is copper, gold, silver, they are good conductor, of course they have similar properties since they are from same group 11 in a periodic table, but aluminium is also a good conductor
I GOT THIS ON MY CLASS 1OTH PHYSICS PRACTICE SHEET OF DRIFT VELOCITY AND IT BIT CONFILCTING INSIDE ME HOW THE FORMULA FORMS AND ALL AND THE TEacher just explains the question of it not the concept but sir you explained us so welll in a fun way and increases our way of thing and it all make sense now thank you very much for providing crash cource \
I learned that the electric field carries by far the greatest part of the energy. In a battery driven circuit, there's only a tiny fraction of electrons necessary to replenish those lost by the battery, resulting in very low drift speeds, a few centimeters per hour.
If the relaxation time is average ,,that means drift velocity is also average?? if drift velocity is average then also current shouldn't be average regarding I=nAVe ???
Hello.... Velocity is distance over time(d/t) .. But the equation you derived has a time parameter directly proportional... Can you please explain that in detail how did that happened....
Bro , gotchu . U see, velocity is distance / time, but also acceleration * time . Also the initial velocities all random , avg to zero , but the change in velocity due to acceleration is all in the same direction. Acceleration is along the direction of force of field
Also regarding the intuition behind why increase in tau corresponds to increase in drift velocity... What if the average time between collision does increase, but the no. of collision itself decreases in such a way that the total time between collision decreases. Is such a scenario possible ?
average time increases and no of collisions also decrease . Then, summation of t/n will increase (denominator decreases and numerator increases) intuitively, it seems possible but when number of collisions decrease, it actually increases the average time.
Yess it is possible taking into consideration that the acceleration for such a situation will be less ie u+at is less which results in less chances of collison and longer duration of the electrons travelling freely accelerating without collisions Hope you would find it helpful
If sum of all initial velocities is zero, then sum of all final velocities at time t must be zero since they are in same direction(vector law) with initial velocity u. HOW DOES THE EQUATION WORK THEN??
the initial velocities all random , average to zero , but the change in velocity due to acceleration is all in the same direction. Acceleration is along the direction of force of field. Regarding your vector addition method , try two opposite initial velocity vectors. And add the same change in velocity vector due to same acceleration to both. Take their average, see that the result is true. The initial parts cancel by the assumption that all initial velocities point in random directions such that their avg is 0,
@@black_jack_meghav BHAI PAHLE CASE ME MOTION RANDOM HAI . TO SUM 0 AA RHA H KYUKI KOI EXTERNAL ACCLERATION NHI H SYSTEM ME PR 2ND CASE ME ACCLERATION AA GYA TO SARE ELECTRON DRIFT HONGE AUR EK TRF CHALENGE TO SUM KAISE 0 HOGA
The final formula is correct but the method is wrong. You are taking drift velocity as average of velocities of a free electron just before collisions. This is a wrong approach because the electron has velocities at other times too, and you should not ignore them. This problem and a correct method of derivation have been discussed in some videos.
hey, just have a small question. isn't the electric field is exerting acceleration at electrons at every moment in time period t? so how does relaxlion time T influence the drift velocity through all time T?
As we know since the average time between two collision is relaxation time which is the average of t hence it is substituted in the final equation in place of t average
Why do you have to be so rude? Mind your own business. If he likes doing an American accent, let him. It's his choice. And you're nobody to comment on that. Please be nice. He's doing a fantastic job out there for all of us. So have some gratitude.
@@ishitabhattacharyya1538 so let me tell u something the video was in public domain and i have all the rights to comment whatever i want and who r you to tell me what to do . If i commented on his video he can reply me back if he wants to,he is not unsound mind and who r u. FYI it was just for fun
Mahesh sir, I survived 12th onnnnnly becz of youu. I am a person who cannot move to another topic without understanding it till the roots and this was pretty difficult for me since i found no perfect explaination to why things were the way they are. Ever since i got a hand on your videos, life has been great. I smile as wide as i can at the end of each video. And the satisfaction that i get on understanding a concept is enormous. And i owe that all to youhh! Thankyou so much for making 12th interestinggg....So much love from chennai❤❤❤❤❤❤
Finally found someone like me who focuses on understanding rather than mugging up and just go on😅
Same....without understanding one topic I don't even feel like reading other things
Ur my senior Ig..but it's nice to see some ppl like me
I really love these concepts... it's just really fascinating and I have respect for ppl who found all these theories and also the great teachers who actually put effort in making us understand...
Thank you khan academy!
Btw, I wrote this under this reply since I relate to this...don't misunderstand.
@@hemanth_2006 Also me💔😅
Oh my god
I wasn't thinking there are people relate with me
Me too😊
I just started watching and I didn't realize how time went so fast which is obviously good. There is a saying right, when we have fun the time flies quickly. Yes, indeed it was very interesting and fun to watch this. I don't usually have fun studying but this is a rare case.
I am Neet 2025 student and it really wonderful ❤....
Thank you lot sir 🙏
Such tender voice with finesse. Sublime explanation Sir.
Damn
That was perfect 💯
I think ur name is ram?!....u r a miracle....ur style of teaching is mesmerizing 😘
He is Mahesh Shenoy
I am an INOI student, but I didn't get a chance to qualified to IOI, so I have to do JEE this next year 2025 in order to get a better college or university, thank you sir for your wonderful explanation❤.
Pls tell explain I have some confusions:
Electrons move in random directions without potential differnce(or electric field ) due to temperature , this is thermal velocity. as they move in random direction , the net current is zero.. simple
Now electric field (constant which is same at every point is applied)this is unlike non unifrom field which decreases with distance since electric force/field is constant acceleration . Well let us consider a scenario where there are no ions to collide. An electron must move in unifrom accerlation from negative to positive terminal since it has no obstacles and veloctiy must increase unifromly let us consider Electic field is E charge e (only considering for one electron in just electric field alone so F=eE and a= F/m= eE/m right this is for one electron..
My questions are :
1. How do we visualise current in a conductor?
2. For example if we take a current of 1microA ok let's condier this it has about 6*10^12 electrons by definition of current these many electrons has to cross the conductor per second but am I wrong to visualise current as a single entity since electrons are spread everywhere in the conductor if drift veloctiy is about 10^-4m/s then how can huge amounts of current or electrons transfer and we get the current appliances working? Is it because of electric field or high speed thermal veloctiy?
Moreover since we consider average veloctiy of electrons then current should also be Avergae since electrons move in different directions we are summing the vector vectorially but the actual directions differ also how the collision result in decelration to maintain same veloctiy how all these take place?even in a simple electric circuit how do we visualise this.. it's confusing I want to know these things
@achuthambi28 look, electrons in a conductor move in random direction, when no electric field is applied, but when Electric field or current is applied from the start of the conductor, electrons will try to move in an opposite direction to that of an electric field, since electrons is a negative charge, the electrons from the end of a conductor will hit some electron that is next to it with some acceleration, and vice versa, it's like tranfer of energy from electron to the other, untill the electrons hit the start where current is applied, actually current is the electrons that are drifted from the end of the conductor towards the start. That's all I know brother
@achuthambi28 if we applied strong current, then they will move more faster, and also depend on conductor, but I don't yet why is copper, gold, silver, they are good conductor, of course they have similar properties since they are from same group 11 in a periodic table, but aluminium is also a good conductor
I GOT THIS ON MY CLASS 1OTH PHYSICS PRACTICE SHEET OF DRIFT VELOCITY AND IT BIT CONFILCTING INSIDE ME HOW THE FORMULA FORMS AND ALL AND THE TEacher just explains the question of it not the concept but sir you explained us so welll in a fun way and increases our way of thing and it all make sense now thank you very much for providing crash cource \
I learned that the electric field carries by far the greatest part of the energy. In a battery driven circuit, there's only a tiny fraction of electrons necessary to replenish those lost by the battery, resulting in very low drift speeds, a few centimeters per hour.
Mahesh Shanoy sir is the best teacher ever seen
Yes he is!!!
Correct
Tq sir
I Clicked and watched only because it's Khan Academy.
Tnku very very much sir.. Keep on doing.. 💘💘🚀🚀
Great Video
Extraordinary
Amazing 🔥🔥
when the velocity us constant!! how can we say it is accelerating...? confusingg
the statement is true but when the particle changes direction it possess accelration
also after every collsion the velocity changes in random direction so the avg drift vel is constant
♥😍 loved it
ye jo 5 dislike aaye hai shayad unacademy walon ke honge 🤣🤣🤣😂😂😂
What a coincidence. I was reading class 10 NCERT Electricity and this video was right on time.
@Bruno Louis
Flixzone? Wassthat?
Well..it's 12th 😅
@@rajaganappathiesshanmugasu3098
Yes but it does have a mention in 10th too and the video is pretty much understandable
@@tejasdeepsingh456 because there is no integration yet
If the relaxation time is average ,,that means drift velocity is also average?? if drift velocity is average then also current shouldn't be average regarding I=nAVe ???
so who acceleration is constant
is the electric field assumed to be constant, if yes then why( shouldn't it be proportional to 1/r^2) ?
Inside a conductor, E is constant after it's connected to a voltage source
Khan I love you
Which app are u using??
What's n?
Number of collision???
yes
sir can u upload a video everyday.
anyway thank you so much
What's mobility which replace e t/m
Hello.... Velocity is distance over time(d/t) .. But the equation you derived has a time parameter directly proportional... Can you please explain that in detail how did that happened....
Bro , gotchu . U see, velocity is distance / time, but also acceleration * time . Also the initial velocities all random , avg to zero , but the change in velocity due to acceleration is all in the same direction. Acceleration is along the direction of force of field
What is N up here and why we are dividing by it
Also regarding the intuition behind why increase in tau corresponds to increase in drift velocity... What if the average time between collision does increase, but the no. of collision itself decreases in such a way that the total time between collision decreases. Is such a scenario possible ?
average time increases and no of collisions also decrease . Then, summation of t/n will increase (denominator decreases and numerator increases)
intuitively, it seems possible but when number of collisions decrease, it actually increases the average time.
Yess it is possible taking into consideration that the acceleration for such a situation will be less ie u+at is less which results in less chances of collison and longer duration of the electrons travelling freely accelerating without collisions
Hope you would find it helpful
If sum of all initial velocities is zero, then sum of all final velocities at time t must be zero since they are in same direction(vector law) with initial velocity u. HOW DOES THE EQUATION WORK THEN??
the initial velocities all random , average to zero , but the change in velocity due to acceleration is all in the same direction. Acceleration is along the direction of force of field.
Regarding your vector addition method , try two opposite initial velocity vectors. And add the same change in velocity vector due to same acceleration to both. Take their average, see that the result is true. The initial parts cancel by the assumption that all initial velocities point in random directions such that their avg is 0,
@@black_jack_meghav BHAI PAHLE CASE ME MOTION RANDOM HAI . TO SUM 0 AA RHA H KYUKI KOI EXTERNAL ACCLERATION NHI H SYSTEM ME PR 2ND CASE ME ACCLERATION AA GYA TO SARE ELECTRON DRIFT HONGE AUR EK TRF CHALENGE TO SUM KAISE 0 HOGA
Guys, what is N?
It's like 1+2+3+4+5+....+n
Where N is some large number
@@sagarshivas298 yeah, but number of what??
no of collisions
The final formula is correct but the method is wrong. You are taking drift velocity as average of velocities of a free electron just before collisions. This is a wrong approach because the electron has velocities at other times too, and you should not ignore them. This problem and a correct method of derivation have been discussed in some videos.
hey, just have a small question. isn't the electric field is exerting acceleration at electrons at every moment in time period t? so how does relaxlion time T influence the drift velocity through all time T?
As we know since the average time between two collision is relaxation time which is the average of t hence it is substituted in the final equation in place of t average
2:10
Here what is N
Me too I want to know😩
But when I'm not mistaken it is free electrons i.e N or n
Drift velocity of all electrons is same
1st veiw 1st like
1:05 no sir we take it very seriously in our lives🤡
😝😶😮😢👻
I see the flag of Italy.
Whats up with the accent bruh
Why u doing American accent if u cant ?
Why do you have to be so rude? Mind your own business. If he likes doing an American accent, let him. It's his choice. And you're nobody to comment on that.
Please be nice. He's doing a fantastic job out there for all of us. So have some gratitude.
@@ishitabhattacharyya1538 so let me tell u something the video was in public domain and i have all the rights to comment whatever i want and who r you to tell me what to do . If i commented on his video he can reply me back if he wants to,he is not unsound mind and who r u. FYI it was just for fun
What is N up here and why we are dividing by it
it is the so of points you take to find the velocity b/w 2 collisions