Same example my dad gave me when I was in 10th. Proud of him coz of his knowledge. No teacher in school or college told me this and now directly by Sir HC Verma
i wish when i was in 11th in 2003 the youtube having such videos and we should not pay 40rs /hour for internet cafe with very slow speed . what i remember is yahoo messenger with ASL Plz (Age Sex and Locaction)
lol in my case as also my physics teacher couldn't answer but she got impressed by it. She was at least a good person without ego and acknowledged her limits. School teachers often teach 2-3 subjects, at least when I was in school, not easy to go in depth.
My father was also an associate professor of Physics, he used to explain me exactly like this during my school and university days... flow of current is like flow of water in pipe and voltage is like how high your tank is, Higher the height of tank/voltage faster the water/current flow. Miss you dad. 😔
Beautifully explained Sir You are one of the few gems in this world who have core knowledge of Physics and can explain it to students in a very easy and effective way
@@Unknown-ei1eg Prof Verma already explained that the current doesn't get reduced.. Because current is nothing but flow of charge.. The movement of charge is slowed down by resistor but it doesn't block any of the charge..
@@masad7315 if democracy is allowed just like flow of charge in conductor and islam provide low resistance then only physics will survive in pakistan or else maulana will destroy ur country
This is an excellent question from anyone starting their electrical study. Across an ideal resistor, Voltage reduces/drops in the direction of current flow - but the current remains the same. This is the basis of KCL/KVL which you must understand to do any circuit analysis. My analogy will also use water through a pipe. The pressure on one end (voltage) forces water (charge) to flow (current) through the pipe. If you squeeze the pipe (resistance) in the middle, the pressure (and the rate of flow) will drop off at the other end. However, all the water will eventually come out (the charge). Note that the rate of flow is also reduced before the point of constriction - in fact through the whole pipe. So, resistance does affect current flow through the entire closed circuit. Without the resistor, current flow will spike to infinity and you will get a short circuit. PS. I'm an EE not a physicist...
So can we make an analogy of resistance in a wire with friction in a surface that if there's friction then our speed (in that case charge's speed) is just in control otherwise we can slip on & on due to its absence (there, current can flow on & on & may result to short circuit) ?
@@abhishekmukherjee4063 You cant take surface as a proper analogy because movement in a surface only contains one variable i.e. the speed of the particle and friction whereas the current is a 3 variable phenomenon, the proper analogy will be a flow of water in a pipe,I guess you can also consider throwing a substance below a building from different heights and different air resistances guess that will work too
I still have doubt sir, Considering your example Voltage is pressure on water Current is flow of electron/water particles per unit time ─────────── 𝗟𝗲𝘁𝘀 𝘀𝗮𝘆 𝘁𝗵𝗶𝘀 𝗶𝘀 𝗮 𝗽𝗶𝗽𝗲 𝗡𝗼𝘄 𝗜 𝗵𝗼𝗹𝗱 𝘁𝗵𝗲 𝗽𝗶𝗽𝗲 𝗶𝗻 𝗯𝗲𝘁𝘄𝗲𝗲𝗻 𝘀𝗼𝗺𝗲𝘄𝗵𝗲𝗿𝗲(𝗿𝗲𝘀𝗶𝘀𝘁𝗮𝗻𝗰𝗲) ───●────────── According to your example when the cross sectional area reduces voltage reduces but current stays the same But if we reduce the cross sectional area of pipe somewhere in between the pressure on water increases and so do the current In same case if you remember when we wash our vehicles sometimes we need more pressurised water so we use our thumb on the end as it cause resistance to the flow but due to this action the pressure on water increases (it covers the longer distance that means water particles passing through a cross sectional area increased that eventually means current increased too) So on this case resistance increased the water flow(current) and pressure (voltage) I am totally confused pls help me out
@@PM-eg7lw stay inside the pipe. Use the faucet (tap) as the resistor analogy. Think of the restriction when closing a tap. Don't confuse the issue - because with fluid dynamics there's nozzles, throttling, valves, Bernoulli effect etc. Good luck
Having read & solved HCV books which explained the Concepts of Physics in a lucid way, I always wanted to thank the human behind it! Sir, we are blessed to have you. Thank you so much.
I have this doubt for so many days and I asked it to my many friends but they didn't satisfied me by their answers but now I can get the satisfaction after watching this video. Sir you are really the God of concept.
I first started reading Concepts of Physics in 1997. It was an amazing book, clear , concise and very useful. But your videos are at a totally different level altogether sir, unparalleled. 👍 . Great gift for students and that too for Free.
This man is undoubtedly the flag bearer of Indian Physics fraternity. He is expert in solving the problems that appear rather obvious to us.. Really you are great sir... Salute to you and your efforts to make the subject so easy which otherwise is definitely not. That is why you get so much respect from all concerned .
Sir, Some points are missing in the explanation, i.e. The volume of charge will remain same not the speed (velocity) in one second. The velocity of the electron (water in analogy) doesn't matter, the most important thing is the volume of charge (electrons) passing through the wire cross-section per second. I just have uploaded a better explanation. th-cam.com/video/KP2UMpjsYGs/w-d-xo.html
Those Who have DISLIKED This Video have no Idea that he is our Honourable Legendary physics Prof HC Verma . Almost all physics students have gone through his books .
So brilliantly explained sir ji I finally realised and understood the concept of resistance after years of schooling, kaash aise teachers hote mere paas bhi😢
@@pranjulunrecognized not continuity equation,sir has considered two different pipes ,do you get it? So a1v1=a2v2 doesnt explain anything in this context,its all about more the area of pipe,less is the resistance offered to water flow thus more is the speed this analogy has nothing to do with equation of continuity
Sir I still didn't get that.. Current is simply flow of electron per unit time And resistor resist or lets say reduce those number of electron passing through a cross sectional area in a unit time That means it reduces the current How current can't be changed after passing through resistor?
@@PM-eg7lw That's what he explained in the video. Since the pipe is a medium through which water flows, its thickness will offer some resistance to the source of water, based upon the resistance the pipe has offered, the water enters inside the pipe; since the pipe is not able to store the water, the amount of water which got inside must come outside the pipe. Likewise, a resistor is not a charge storing device, therefore the current entered in the resistor must leave it with the same magnitude. Resistor offers some resistance to voltage source, the larger the resistance the smaller the current is. Take a voltage source of 1 volt and take a resistance of 1 ohm, the current is 1 ampere, so now if you vary the resistant, the current also varies. Suppose, the resistance is now 2 Ohms, then the current will be 0.5 Ampere; here, resistance was already offered by the resistor that's why current reduced.
The velocity of electrons may differ according to the value of resistor but not the quantity of charge at both the ends and no accumulation takes place inside the resistor.Even the velocity doesn't matter,only the value of current matters at both the ends.Great sir..
Here a Graduate Physicist. Current in fact descreases when it passes through a resistance. What happens it's the time in which that happen is very small. It's called relaxation time, and during that time charge is accumulated near the surface of the resistance, to make the electric field strong in the resisance (more resistance more voltage falls) and then raise the current , until the circuit reaches the stationary regime and the current is constant. The relaxation time of most conductors are incredible small: copper is 10^-17 and water: 10^-6. So usually in most circuits we neglect this effect. Note: This effect can be approximated with a capacitor in parallel with a ideal resistance. But for computing the capacitance you are going to need to solve the full Maxwell equations numerically for the general case.
@Elias Yes, it's right. Anyways I'm going to leave here a detailed example: - Suppose that you connect two resistors of equal length with resistances R1, R2, where R2 > R1 in series with a battery with voltage V. - Initially, the voltage that falls in each resistor is equal and is V/2 . This means that the current in resistor 1 is I1 = V/(2*R1) and in resistor 2 is I2 = V/(2*R2) . Current in resistance 2 is smaller than in resistance one! - So if this happen , Where does the remaining charge go? Answer: It accumulates between the two resistances. In this case the accumulated charge will be positive. This accumulate charge will create a electric field that increase the voltage that falls in R2 and decreases the voltage that falls in R1. As a consequence, I1 will fall and I2 will rise, until we get the stationary result, which is obtained via circuit theory: V1 = V /(R1 + R2) * R1 V2 = V/(R1 + R2) * R2 And the current is equal in both resistances: I1 = I2 = V/(R1 + R2)
Computational Physics Computational Physics Your explanation best fits for graduate students, for those who have learned Maxwell equations and equation of continuity. But for 10th standard students, his explanation is better.
i=V/R , higher resistance decreases the flow(volume of electrons) of current passing through it, but any resistor can't eat electrons, so the current on both sides will remain same.
Sir, Some points are missing in the explanation, i.e. The volume of charge will remain same not the speed (velocity). The velocity of the electron doesn't matter, the most important thing is the volume of charge (electrons) passing through the wire cross-section. I just have uploaded a better explanation.
Amount of water in given time i.e. Discharge(Area×velocity) is constant. Less area will give more velocity to keep discharge constant. Velocity is the distance that water travels in given time, it may change according to area of cross-section. Current(amount of charge in given time) is similar to Discharge which is constant. You're a great teacher sir, highly inspired by your teaching methods.🙏
Truly, this is a deep question, the answer is far more deeper than the question. Resistance offered is mainly at the interface of water with another material surface in pipes, the same way current flow has a dampening effect at a metallic structure level band of energy levels. The rest of electrons are in a different part of energy transfer path, there is a term called mean free path and collision frequency which provides a net effect resistance or conductance. As long as EMF is applied or induced, currents are produced. The battery/source eventually lose out if not coninuously replenished. At that time, di/dt =/=0, or keeps dropping, current dies after a specific time.
In our education system, textbooks of lower standards creates confusion in view of teaching the students in a easy way ,but when at higher level we get to know the reality we are not even concerned to accept it, I thinks these types of misconception should be sorted at the first time to not crate any mess further
Hello sir , It would be really really great for all physics students if you take lectures completing the two volumes of “concepts of physics “ , it would be really helpful. Sir as your books ( Two volumes ) are indispensable for all of us , your lectures will be ! Every student aspirant wether Neet or JEE has dream to learn from you , behalf of all students of India Sir do consider my humble request .. Shalem .
Thats what makes you real practical physicist sir! You're awesome as always! 👏 From legendary book concepts of physics 1,2 to your video lectures. We all really miss you in IIT Kanpur campus! 😁 Still we love to brush our concepts from your lectures! Lots of love and respect Muba, geeky Engineer
I had the same question in my mind since i started studying current electricity but always ignored it. I found this video today and it was really helpful. Thank you so much sir. 🙏
I am surly agreed with your answer sir, sorry But then what will be the use of resistor ? What difference it will make in using it and not using it in a circuit ?
NOPE , BASICALLY RESISTOR IS A METAL AND METAL HAS SOME ELECTRONS IN IT , SO WHEN A BATTERY IS CONNECTED TO A RESISTOR IT CREATES POTENTIAL DIFFERENCE ACROSS THE RESISTOR AS A RESLUT ELECTRONS WHICH ARE NEGATIVELY CHARGED GET ATTRACTED TO POSITIVE TERMINAL OF BATTERY AND START MOVING TOWARDS THE + TERMINAL AND THIS MOVEMENT OF ELECTRONS RESULTS CURRENT
Verma sir, you explain this question so wonderful. Theoretically it can be said if current decrease in unit time then charge will also decrease in that time (because current is charge per unit time ) which opposes the law of conservation of charge . Hence current remains unchanged. Thanks
I have one stupid answer..🔥 (READ IT U'll BE Satisfied) Many are saying one word answer as charge conservation.. this isn't true completely. which means what charges are going in are coming out. But current is the rate of flow of charge, the time taken by the charges to complete the journey in case of 0 resistance (no collision) will be lesser than with some resistance. I=Q/t => I inversely proportional to time. Since time taken is increased with adding up of resistance. Hence current (charge per unit time) will decrease. Problem with what sir told is: It should be even after resistance the amount of charge coming out is same as it's going in.. not the current which is time dependent.🙏🏻🙏🏻🙏🏻
Though I'm convinced with the logic given by sir but don't u think that there's some mistake occurred in the explanation of continuity equation....?? 🤔 Let me know if u think so...🤞
@@jdgoel4817 (I’m not professionally trained with electronics so this might be very wrong, it’s how I currently view this). Keeping this analogy going; whenever you bump into someone or something you convert your movement into heat. You then start walking again, because you aren’t where you want to be and there is space somewhere else that just opened up. This doesn’t change that the amount of people going into the crowded place is always the same as the amount of people going out. As for where the energy for the heat comes from, that is from the pressure pushing the people in and the pressure pulling the people out. Because the person lost their kinetic energy bumping into something, it must (in a sense) “consume” some of the pressure to get moving again. Pressure is similar to the voltage difference between two places.
Asked this question in my school days to teacher and she just repeated the same line again without explaining ....now i got it after a couple of years.
The current basically has no other place to go and therefore it will go through and come out of the resistance. To reduce the current within this setup, you will need to provide a different path for it to flow. Like connecting a parallel wire across the resistance, which can choose to include its own resistance. In that case, the current will split and more current will flow through the path of lesser resistance. Either way, when a current flows across a resistance, we loose voltage across it. And therefore, there is lesser voltage at the point where the current exits from the resistance in comparison to the point where it entered. This is because there was energy expended over the resistance. Now suppose you have a current flowing through a resistance. And suppose you are able to gradually increase the resistance. You will observe that the current also decreases gradually. But whatever current came out of the battery in each instance will flow in and out of the resistance without change. In other words, the battery or voltage source will always decide to push out a current whose value is calculated by first internally _feeling_ the net resistance in the circuit before the current starts to flow. This internal calculation of nature is just ohm's law. This means that if the initial resistance is very very high (imagine a rubber string instead of a copper wire), the voltage source will decide it cannot push a current through the circuit and no current will flow. If however, you now increase the voltage tremendously, there will come a point when it maybe possible to push a current even through this high resistance circuit. But the main idea to understand is - whatever current the voltage source pushes out, after internally seeing the net resistance, it will flow through the loop and complete the circuit.
Best comment. HC sir is unable to explain here. If resistance doesn't oppose the flow of current, than why bulb lights up? The tungsten wire provide great resistance and in the process gets heated up. So here electric energy is being converted into heat and light energy by resistance.
Drift velocity of electrons.Its the basics and given in school and college books but the thing is we never read to understand...we read to get pass with good numbers. We read everything but we don't try to go deeply into anything and this is where we make faults. Nice brief explanation by H.C VERMA SIR.
Textbooks should never say resistance opposes current....it leads to misconcepts 1)...resistance consumes energy(voltage×q passed) 2)...from where does this energy come?...from collision of electrons during moving under electric field....same energy which is provided by electric field(q×E×d) is lost in collisions... 3)That's why we have V(work done by field that accelerates unit charge in its journey)=iR(energy lost in collisions in resistance)..... You think yourself....all energy provided is lost in collisions.... that is why we have a constant value of i..{i=neavd..constant current means constant velocity and constant velocity means no net work has been done...i.e energy gained=energy lost}.. 4)..resistance is basically dependent on the no. of times electron loses its energy in collisions during its journey...and has to accelerate again....this is from where R=rho L/A comes....if there was no resistance.... all electrons would never collide....no start stop journey....in a fraction, all together will reach low potential.... Giving rise to infinite current(short circuit).....similarly you can think of infinite resistance....journey of electrons never starts really...as they just keep colliding... 5)so the question was....why is current not decreased by resistance?....electron perform start(due to field)-stop(due to collision) motion through out the resistance.....if it decelerates due to collision... Then it also accelerates due to electric field....giving rise to a average value of current, which is same throughout the resistance.... More resistance means...it stops more often then it accelerates giving rise to a low value of current, but even then, it is uniform throughout the resistance.....i.e.overall value of current decreases...but not current itself........ 6)many people also have doubt that V is work done per unit charge While i×r accounts for total no of charges crossing × resistance....how can two things be equal.......one is concerned with single charge and one with all charges crossing!...... Ans is simple......i×r means neAvd×r.....i.e. it has both n and vd(drift velocity) terms in it....say n=1 and vd=2......then it signifies that wow vd is 2 of each electron.....hence good field must be acting on it....hence potential difference is good......now interchange and say n=2 and vd=1....hmm...vd is not high this time of this electron....but heyy!...it is also more crowded this time, thus vd=1 is also commendable here...there must be good potential applied. Which is true as 2×1=1×2....i.e potential is actually same in both cases....overall I conclude by saying....even though i×r includes 'no. of charge crossing term'....,but it has nothing to do with the no of charges crossing.... And only with the crowdness one unit charge feels while moving ......concluding that both potential and ir term are talking about 1 unit charge only....(one of energy gained, one of energy lost)..and hence can be equated to give us beautiful ohms law...which is nothing but a form of energy conservation!!!!... Thankyou😊 Ps: Many people are saying...one word answer is charge conservation....why?... By this explanation....cant charges lose their energy and stay in there afterwards?...i dont seem to get this explanation... resistance is not a pipe which will burst if more water is in it than volume...get me correct please...anyone?
@@jyotiparihar5454 I think that he , want to say that when current pass through that circuit amount ( value of current) differ. Waise mujhe bhi jyada samajh Nahi aaya. Good morning @jyothi
@@MultiSpidyman You're right, provided the resistance is increasing. Keeping the resistance constant, there wouldn't be any change in rate of flow of charge.
When resistance comes into picture, there some electric field associated with resistance which hinders path of incoming protons (or opposite flowing electrons) & hence there's some change in electric current.
@@kanyonful if the flow is smoth the speed of water will increase at narrower region. It will make sure same volume of water passes through every cross section whether large or small in a given time.
Yes.But sir NEVER said that speed is SAME in BOTH pipes.He has even used 'v1' for short pipes and 'v2' for larger pipe.The concept is speed whether v1 in small pipe or v2 in large pipe remains same in exit and entry. Hope it helps!!
To ask doubts to teachers & pursue your query till getting answers is the very much key for students or everyone to learn. It's an real satisfaction. This is what I think. Thank you so much sir... 🙏
But sir, according to the continuity rule, water will flow with a larger speed in a narrower pipe. av = constant. Please clarify your explanation when you say that the speed will be smaller in a narrower tube. Water is incompressible as we know, from the same tap, it will flow swiftly in a narrow tube compared to that in a wider tube.
If the widths at any two points in the pipe are the same, the speeds of water at those two points will also be the same. If you have a pipe whose width varies at different points, the speed of water in the pipe will vary accordingly. Smaller at wider points and larger at narrower points.
see, you can't look at this concept in isolation, to understand let's take an example of simple circuit, 10 V battery, and 1-ohm resistor, according to ohms law, u will get 10 amp current from battery which will pass through 1 ohms resistor, now if u replace 1 ohms resistor with 2 ohms, according to ohms law u will get 5 amps current flowing through battery and resistor, So, a resistor offers resistance to the overall circuit, and current of that circuit is based on that overall opposing force, but once resistor and driving force (here it is the battery) agrees to common current, it flows through the entire system. now coming to, slowing down of charges, there is no point of slowing down of charges, as they already move very little, but it is the message of movement of charges which moves at almost the speed of light.
Thank you very much sir my 10th boards were coming I was so much confused but your analogy of water pipe helped me understanding it and I made my own analogy of something like air coming out of a balloon thing.
When you put a positive voltage on the ends of a resistor, electrons flow through it. The atoms in the atomic lattice of the resistor also move because of the temperature of the operating area. The moving atoms and electrons often bump together and the electron-flow gets slower, the potential energy(that´s why it's called potential) gets converted to heat. Voltage is just a potential difference. That's also the reason why resistance changes with temperature and why resistors get hot when large currents flow through them.
Greater the pipe diameter less the speed, smaller the diameter larger the speed of water. This is due to equation of continuity.plz sir correct the concept as the video is saying it opposite.
I think Here it means, smaller the diameter, greater will be the resistance because of increased collisions, and ultimately the flow will be resisted and slowed down.
@@learningwithtahira5920 But V2 will still be greater than V1 for the smaller pipe so it doesn't matter if the smaller pipe offered more chance of collisions
Buy his books and spend 10% on reading and 90% on solving questions. I also did this mistake and I took so so much time just reading and analysing but it's not so deep meaning as much I thought so if you reading his books give more time in solving. 🙏😃
Lot many comments in the comment section are speaking about this analogy being an untrue and non exact one. Reasons being cited are "AS PER CONTINUITY EQUATION FLOW SHOULD BE MORE FAST IN NARROWER PIPE" EXPLANATION: If you ever study fluid mechanics in detail then you will come across equation called "DARCY WEISBACH EQUATION" H=flV^2/2gD... H is the head loss , V is the speed of fluid , D is the diameter of the pipe , f is the friction factor. SO IF HEAD LOSS IS SAME (WHICH IS IN THE PRESENT CASE AS RESERVIOUR IS SAME IN BOTH CASES ) THE SPEED IS DIRECTLY PROPORTIONAL TO THE DIAMETER * D* OF THE PIPE . SO SPEED WILL BE LARGER IN LARGE DIAMETERED PIPE UNDOUBTEDLY!!. ......................................... THEIR IS NO SCOPE FOR APPLYING CONTINUITY EQUATION OVER HERE AS THE PIPE CROSS SECTION REMAINS SAME IN BOTH CASES . THEIR IS NOTHING LIKE SMALL- BIG PIPE CONNECT IN PRESENT CASE ... SO DON'T THINK OF CONTINUITY ANY WAYS .
no brother...lets consider continuity equation flowrate what he tried to mean is that flowrate will be same in all crossesections of pipe.flowrate can be related to current here..speed cant be related to current.. Q=AV.. so when area of crossection decreases,velocity(speed) has to increase to keep flowrate same... the same when area increases velocity has to decrease inorder to keep flowrate same..the flowrate can be related to current not the speed..
Continuity equation can only be used if discharge remains const. For a pipe connected to a tap or something the discharge is variable. So continuity eqn can't be used. For small discharge, velocity will be less.
Sir, I'm Naveen Pandey the student of class 10th. Sir when we have the larger cross sectional area the velocity of water becomes decrease when water comes out from a tap or a pipe and when the cross-sectional area of the tap or pipe is small , the velocity of water increases. But sir when we turn on the tap a little, velocity of water from the tap is also little and when we open the tap completely, the velocity of water also increases why this happens?
You can understand by the equation of discharge Q =AV Where, Q= Discharge (flow) of water A= cross sectional area of pipe V= velocity of water So, we can conclude that cross sectional area of pipe is inversely proportional to the velocity of the water
Uh can also say tht resistance is directly proportional to area of cross section so when the Area of Cross section is more thre will b more resistance nd decrease in velocity an when area of cross section is small thre will b less resistance and the velocity will increase If uh agree reply plz...
We can not say that air is insulator. Because electricity produced in rain which is of very high voltage is conducted by air. So air is a "BAD CONDUCTOR" of heat and not an insulator. That's the reason behind this.
@@RameshKumar-xd1lm Wrong! Air is an insulator as well as a dielectric. Experiments prove that electric field tends to decrease in the presence of air. But,remains same in the presence of vaccum.
Thank you sir..I had asked this question to my teacher many times but I cannot understand what he wants to explain but finally I got it why current does not decrease...thank you so much
Why it's difficult to understand? It's a well known fact that current remains same in the entire loop of a circuit. Current is how fast the charge travels, that is speed of charge travel. For e.g: when current enters the resistor, 10 C passed every second, and when it left resistor 5 C passed a point every half second, so rate of transfer of charge remained same because charge density changed. Before entrance less charge carriers (electrons, ions, etc) were travelling with high speed and at exit more charge carriers travelled with low speed (because of congestion), so total charge passing a point per second remained same.
Make sure you understand the difference between current and charge. You may feel the difference is arbitrary now, but if you want any degree with ECE, you'll do well to notice now that it isn't.
As much as i respect his teaching i have to say the explanation isn't completely accurate, the reason v1=v2 in the narrow pipe is because the pipe was always narrow from the start that is not the case with resistance, the resistance is offered somewhere in the middle.
Its still valid. Consider resistor as a large pipe connected to a narrow pipe connected which is connected to a large pipe . The velocity in first large pipe is v1 and the narrow pipe has velocity v2 on both ends then the velocitiy of the water comming from the last large pipe must be v1(i.e current going in=current going out)
It's just an analogy my friend it's not 100% explaining what is happening but like I said it's an analogy meaning it's similar to that just not exactly the same
Lol as soon as the resistor is added it is in the same loop so it is a correct analogy, Consider you can walk 500m in a minute in general, but you met a friend and you wasted a fraction amount of time in shaking hands(though not recommended at this time😂) and you were delayed by 10 sec, Right from 0m to 500m your friend can be anywhere in between and still can delay you for ten seconds.If you're going to meet a friend always than you will always be delayed!
Ya if the amount of water is constant in both the pipes then water in narrow pipe will have greater speed, it means greater voltage with greater resistance and constant current, hence ohms law is proved🥳 R=V/I
We are not talking bout fluid mechanics here ...it is not an anology so do not compare that with it ...he is just trying to explain resistance by this .
@@doctorcapacitor7932 it is only an analogy. He knows about fluid mechanics more then anyone in this country.☺️ He would not meant what you understood. The thing you are saying about fluid mechanics only works in laminar flow. But in real life most of the fluids including that from a tap follows turbulent flow. V is inversely proportional to the cross section only in laminar flow. In turbulent flow, v is directly proportional to the cross section . Same as in a thicker wire resistance is less while in a narrower wire resistance is high. This is only an analogy. I am also a student and not sure if we can define flow of current in terms of laminar flow or turbulent flow. Btw, this a very nice question
Whoever has asked this question one thing for sure he or she doesn't study for marks but for just pure knowledge of science..this is called basics..👍
True bRo
uske hisab se mein to purest of the purest knpwledge k liye padh raha tha.......kuki ye logic mene khud heee discover krr liya tha 10th claas mein🤣
@@akshayranga2058 to kuch fayda hua #ranchordas bne ya #silencer bne ho 🤣😅
Thanks bro
@@rohinibhavsar6615 why thanks??
I have a Masters degree in Electrical Engineering and still didnt know about this. Happy to learn it from you sir.
What!?
Btw happy learning!
coz u r a very honest student.
@noname And you are salty
It's becoz crossection are infinite ann
That's so wrong on so many levels😂😂😂😂
The Smile On Verma Sir's Face during explaination reminds me that Physics is not dangerous.
Comment of the century ❤️🔥
Highly Underrated comment
😊
Is this official channel 🙄?
@@satyaprakashray9909 it is
Same example my dad gave me when I was in 10th. Proud of him coz of his knowledge. No teacher in school or college told me this and now directly by Sir HC Verma
Bcs in those days they accumalated knowledge if u ask ur skl teacher they wont say they jzt accumulated degress
@@mayurpatil7333 Actually now I understand what was the class of engineers from that era when literally Mumbai had only 2-3 Engineering Colleges. :/
@@sohamkulkarni7207 tru and the best example u can take is roads then and now
Everyone gives this lol
i wish when i was in 11th in 2003 the youtube having such videos and we should not pay 40rs /hour for internet cafe with very slow speed . what i remember is yahoo messenger with ASL Plz (Age Sex and Locaction)
This was a question that I asked my teacher in my 9th standard ... And she answered .. why will it change ,it will not ... And I just nodded.
Lol... Rofl.... My school physics teacher used to tell me, wait i shall tell you later , whenever i went with any mcq doubts.
haha .. yes
@@kingbing3315 baah 😂😂
lol in my case as also my physics teacher couldn't answer but she got impressed by it. She was at least a good person without ego and acknowledged her limits.
School teachers often teach 2-3 subjects, at least when I was in school, not easy to go in depth.
Y'all people even asked such questions 😂
Such a humble person....responds to questions, which can cause problems even if the concept is simple.....respect...😍😍😍😍
Everything is simple brother...when you understand it
Physics is easiest if you really want to learn it. 😊
Hardworking & clarity needed.
My father was also an associate professor of Physics, he used to explain me exactly like this during my school and university days... flow of current is like flow of water in pipe and voltage is like how high your tank is, Higher the height of tank/voltage faster the water/current flow. Miss you dad. 😔
Superb
Sorry.
Sorry.
मार गाया😅😅😂😂😂
@@Yeuiudjd321you are so insensitive, death koi hasne ki baat nahi hai
No time pass, no long lectures, straight to the point, legend❤️
Other people in lockdown - tik tok vs TH-cam
H c verma sir in lockdown - how the current remains same after passing through a resistance
"Tik tok vs you tube" was important to restrict aberration of students....
😂
What is tiktok vs TH-cam??
Explain
@@tanayagrawal5485 Yt won!! Vishay khatam!
@@aadityapatil1354 ohh
When did it happen
I like to see his smile and happiness while answering the questions.
He seems really kind and humble.
Wow..video is being uploaded after 2 at night and still hundreds of student came to watch it.!!!
power of knowledge
That’s true. Power of legend teaching physics
@Keshav Baviskar Jalgaon, Maharashtra
Because its HC Verma sir!!!
Saumya Singh true. I make videos too if you wanna check it out you know
Beautifully explained Sir
You are one of the few gems in this world who have core knowledge of Physics and can explain it to students in a very easy and effective way
I had this same doubt when I was in class 12...And I understood the meaning of resistance during my engineering...
@Physics and Mathematics Geeks every engineering student isn't a iitian
I think he is an private college student as he don't have his basics clear because to clear IIT- JEE we have to have a good grip in all subjects
@@its_rohit_0506 You cannot say that private college students have weaker concepts.
@@its_rohit_0506 even if we do engineering from a shit college, we can get hire in Google too!
@@its_rohit_0506 rofl. Oh bhai zameen pe raho. Dont stay aloft on that cloud. You will fall down.
Hmmm I never had this doubt even when I was studying engineering! This kid is going to be pretty good in the future!
It wasn't a good question because he doesn't know that current is nothing but flow of charge and resistors don't hold charge..
I actually thought about this question as a kid but never asked. Almost 5 years have passed since my graduation in engg.
@@amansinha1443 But current toh reduce hota hai resistor se pass hone ke baad... Please can you explain...
@@Unknown-ei1eg Prof Verma already explained that the current doesn't get reduced.. Because current is nothing but flow of charge.. The movement of charge is slowed down by resistor but it doesn't block any of the charge..
@@amansinha1443 😲 oh!!
Thanks Brother 🙏
HC Verma is true Physics legend.Huge respect from Pakistan 🇵🇰🇵🇰🇵🇰🇵🇰🇵🇰
India mein sare hi legend hota hai😂😂
Is HC Verma Sir's book used in Pakistan also..!!
@@ThePhysicsTrain no
@@masad7315 if democracy is allowed just like flow of charge in conductor and islam provide low resistance then only physics will survive in pakistan or else maulana will destroy ur country
We are always brothers bro.
I'm a commerce student and understood this concept completely. Such a wonderful explanation by HC Verma sir. Great fan of his teaching!!
@Mohammad Shaikh ikr i was also confused like what about equation of continuity isn't it the opposite the narrower cross section must have more speed?
This is an excellent question from anyone starting their electrical study.
Across an ideal resistor, Voltage reduces/drops in the direction of current flow - but the current remains the same.
This is the basis of KCL/KVL which you must understand to do any circuit analysis.
My analogy will also use water through a pipe. The pressure on one end (voltage) forces water (charge) to flow (current) through the pipe. If you squeeze the pipe (resistance) in the middle, the pressure (and the rate of flow) will drop off at the other end. However, all the water will eventually come out (the charge). Note that the rate of flow is also reduced before the point of constriction - in fact through the whole pipe. So, resistance does affect current flow through the entire closed circuit. Without the resistor, current flow will spike to infinity and you will get a short circuit.
PS. I'm an EE not a physicist...
To the point and exact answer
Whoever wondering this question,this is the exact answer
So can we make an analogy of resistance in a wire with friction in a surface that if there's friction then our speed (in that case charge's speed) is just in control otherwise we can slip on & on due to its absence (there, current can flow on & on & may result to short circuit) ?
@@abhishekmukherjee4063 You cant take surface as a proper analogy because movement in a surface only contains one variable i.e. the speed of the particle and friction whereas the current is a 3 variable phenomenon, the proper analogy will be a flow of water in a pipe,I guess you can also consider throwing a substance below a building from different heights and different air resistances guess that will work too
I still have doubt sir,
Considering your example
Voltage is pressure on water
Current is flow of electron/water particles per unit time
───────────
𝗟𝗲𝘁𝘀 𝘀𝗮𝘆 𝘁𝗵𝗶𝘀 𝗶𝘀 𝗮 𝗽𝗶𝗽𝗲
𝗡𝗼𝘄 𝗜 𝗵𝗼𝗹𝗱 𝘁𝗵𝗲 𝗽𝗶𝗽𝗲 𝗶𝗻 𝗯𝗲𝘁𝘄𝗲𝗲𝗻 𝘀𝗼𝗺𝗲𝘄𝗵𝗲𝗿𝗲(𝗿𝗲𝘀𝗶𝘀𝘁𝗮𝗻𝗰𝗲)
───●──────────
According to your example when the cross sectional area reduces voltage reduces but current stays the same
But if we reduce the cross sectional area of pipe somewhere in between the pressure on water increases and so do the current
In same case
if you remember when we wash our vehicles sometimes we need more pressurised water so we use our thumb on the end as it cause resistance to the flow but due to this action the pressure on water increases (it covers the longer distance that means water particles passing through a cross sectional area increased that eventually means current increased too)
So on this case resistance increased the water flow(current) and pressure (voltage)
I am totally confused pls help me out
@@PM-eg7lw stay inside the pipe. Use the faucet (tap) as the resistor analogy. Think of the restriction when closing a tap. Don't confuse the issue - because with fluid dynamics there's nozzles, throttling, valves, Bernoulli effect etc.
Good luck
Having read & solved HCV books which explained the Concepts of Physics in a lucid way, I always wanted to thank the human behind it! Sir, we are blessed to have you. Thank you so much.
H C Verma Sir's video's has no.. ads..
Shows his afforts😉❤️
yea 🔥 HC Verma sir always legend
I have this doubt for so many days and I asked it to my many friends but they didn't satisfied me by their answers but now I can get the satisfaction after watching this video. Sir you are really the God of concept.
I first started reading Concepts of Physics in 1997. It was an amazing book, clear , concise and very useful. But your videos are at a totally different level altogether sir, unparalleled. 👍 . Great gift for students and that too for Free.
This man is undoubtedly the flag bearer of Indian Physics fraternity. He is expert in solving the problems that appear rather obvious to us.. Really you are great sir... Salute to you and your efforts to make the subject so easy which otherwise is definitely not. That is why you get so much respect from all concerned .
Uploading at 2 am at night, so that it’s accessible to all students in the morning.
*Amazing dedication*
*Making our Sunday mornings*
Your small board is very cute.....
Hc verma is cuter than his cute board
His smile is way cuter than the board 🤗
Sir, Some points are missing in the explanation, i.e. The volume of charge will remain same not the speed (velocity) in one second. The velocity of the electron (water in analogy) doesn't matter, the most important thing is the volume of charge (electrons) passing through the wire cross-section per second.
I just have uploaded a better explanation.
th-cam.com/video/KP2UMpjsYGs/w-d-xo.html
0:34
Honest question, why do people end a sentence with this "...."? Or, instead of using a comma, use this "...."?
Those Who have DISLIKED This Video have no Idea that he is our Honourable Legendary physics Prof HC Verma . Almost all physics students have gone through his books .
Yes, and for some, he gruesomely butchered the concept.
@@parthverma4534 ☠️☠️
bcz of his books ppl has disliked this video
@@parthverma4534 you are absolutely correct my friend
@@parthverma4534 could you explain please? I haven't done HC Verma yet lol
First time youtube recommendation give me the right video which I was really searching for 🙃🙃
So brilliantly explained sir ji I finally realised and understood the concept of resistance after years of schooling, kaash aise teachers hote mere paas bhi😢
Had you been my teacher, I would have had a different life today. Just love the way you teach.
Resistance explained by BERNOULLIS theorem 😂
Good boi
not bernoulli's equation but continuity equation.
Bro it is continuity equation
@@umangchourasia3002 a1v1= a2v2😂
@@pranjulunrecognized not continuity equation,sir has considered two different pipes ,do you get it? So a1v1=a2v2 doesnt explain anything in this context,its all about more the area of pipe,less is the resistance offered to water flow thus more is the speed
this analogy has nothing to do with equation of continuity
I have diploma & B.E. in Electrical Engineering, but I never thought that this concept could be explained with this simplicity.
Sir, you are a legend.
That's coz u aren't thought these basics & most of us don't care enough.
Can you explain in simple words to. Me what you understand?
@@pravinkamble4431 Simply put current does change when resistance is added but the changed current flows through every component of the circuit.
Sir I still didn't get that..
Current is simply flow of electron per unit time
And resistor resist or lets say reduce those number of electron passing through a cross sectional area in a unit time
That means it reduces the current
How current can't be changed after passing through resistor?
@@PM-eg7lw That's what he explained in the video. Since the pipe is a medium through which water flows, its thickness will offer some resistance to the source of water, based upon the resistance the pipe has offered, the water enters inside the pipe; since the pipe is not able to store the water, the amount of water which got inside must come outside the pipe.
Likewise, a resistor is not a charge storing device, therefore the current entered in the resistor must leave it with the same magnitude. Resistor offers some resistance to voltage source, the larger the resistance the smaller the current is. Take a voltage source of 1 volt and take a resistance of 1 ohm, the current is 1 ampere, so now if you vary the resistant, the current also varies. Suppose, the resistance is now 2 Ohms, then the current will be 0.5 Ampere; here, resistance was already offered by the resistor that's why current reduced.
Don't underestimate the power of thekua
Are are 😂✌🏻
Yes!
I just read this chapter, had the same question, and TH-cam recommend this 😲
RCB QUALIFIED PLAYOFFS
YO WE TWO FANS ?
Your phone is listening u😈
They even know about your all activities 😏😏
@@vishnoiindar7338 no, i was away from my phone, maybe a coincidence...😁
Same😅
The velocity of electrons may differ according to the value of resistor but not the quantity of charge at both the ends and no accumulation takes place inside the resistor.Even the velocity doesn't matter,only the value of current matters at both the ends.Great sir..
Exactly..👌👌
Thanks sir
Exactly my thoughts
Best teacher ever ❤️ thank you so much sir 🙏💕love you
This has to be the most exciting lecture i ever saw to be honest 😊😊
Here a Graduate Physicist.
Current in fact descreases when it passes through a resistance.
What happens it's the time in which that happen is very small. It's called relaxation time, and during that time charge is accumulated near the surface of the resistance, to make the electric field strong in the resisance (more resistance more voltage falls) and then raise the current , until the circuit reaches the stationary regime and the current is constant.
The relaxation time of most conductors are incredible small: copper is 10^-17 and water: 10^-6. So usually in most circuits we neglect this effect.
Note: This effect can be approximated with a capacitor in parallel with a ideal resistance. But for computing the capacitance you are going to need to solve the full Maxwell equations numerically for the general case.
This is the correct explanation.. actually rate of flow of charges decreases that's current..
@Elias Yes, it's right.
Anyways I'm going to leave here a detailed example:
- Suppose that you connect two resistors of equal length with resistances R1, R2, where R2 > R1 in series with a battery with voltage V.
- Initially, the voltage that falls in each resistor is equal and is V/2 . This means that the current in resistor 1 is I1 = V/(2*R1) and in resistor 2 is I2 = V/(2*R2) . Current in resistance 2 is smaller than in resistance one!
- So if this happen , Where does the remaining charge go?
Answer: It accumulates between the two resistances. In this case the accumulated charge will be positive. This accumulate charge will create a electric field that increase the voltage that falls in R2 and decreases the voltage that falls in R1. As a consequence, I1 will fall and I2 will rise, until we get the stationary result, which is obtained via circuit theory:
V1 = V /(R1 + R2) * R1
V2 = V/(R1 + R2) * R2
And the current is equal in both resistances:
I1 = I2 = V/(R1 + R2)
@Elias flow of current is quantum phenomena and it cannot be understood by even by a graduate. In basic book we talk very ideally.
Computational Physics Computational Physics Your explanation best fits for graduate students, for those who have learned Maxwell equations and equation of continuity. But for 10th standard students, his explanation is better.
@@comprehensivemathsscience1217 Of course!
I just want to add this commentary for the ones who wants to know more.
i=V/R , higher resistance decreases the flow(volume of electrons) of current passing through it, but any resistor can't eat electrons, so the current on both sides will remain same.
Better explanation then that of HCV.
But sir is explaining in Basic way .And the question is asked by 10th grade student so ..
@@shiva_iitkgp right, sir students ke level pe aa k explain krte hein, thats why he is Padamsri Prof. HV Verma
@@Baljindersingh-nb9jy Yes, And one question is for you that what is the level of research at IITK .
Means environment for research.
Sir, Some points are missing in the explanation, i.e. The volume of charge will remain same not the speed (velocity). The velocity of the electron doesn't matter, the most important thing is the volume of charge (electrons) passing through the wire cross-section.
I just have uploaded a better explanation.
Amount of water in given time i.e. Discharge(Area×velocity) is constant.
Less area will give more velocity to keep discharge constant.
Velocity is the distance that water travels in given time, it may change according to area of cross-section.
Current(amount of charge in given time) is similar to Discharge which is constant.
You're a great teacher sir, highly inspired by your teaching methods.🙏
Yep, this thing I did not understand. The analogy was kinda wrong. A better one would be with cars on a sleek road.
@@intothenight69no..because after resistance the speed of cars should be more
Very nice explanation,we r lucky that we are having internet to reach such a genius
Truly, this is a deep question, the answer is far more deeper than the question. Resistance offered is mainly at the interface of water with another material surface in pipes, the same way current flow has a dampening effect at a metallic structure level band of energy levels. The rest of electrons are in a different part of energy transfer path, there is a term called mean free path and collision frequency which provides a net effect resistance or conductance.
As long as EMF is applied or induced, currents are produced. The battery/source eventually lose out if not coninuously replenished. At that time, di/dt =/=0, or keeps dropping, current dies after a specific time.
My Physics sir himself were your students and his speech resembles exactly like you.
His name is *Jata Shankar Mishra*
I asked this same question when I was in 9th to my school teacher ..she slapped me
@@TheHariPutraOfficially sounds like you didn't get slapped hard enough. are you kidding me?
@@ATX_Engineer I was slapped hard
@@TheHariPutraOfficially share this video to her and ask why you were slapped
@@TheHariPutraOfficially ptu lagta hai bada gyani tha .....ye chapter to class 10th mein hai 🤔🤔 app 9th mein padh liye .....sounds strange
Comment has been taken down due to hate spread....but can be reuploaded on demand
Nice bhai.
Great hard work you did.
Preparing for what?
Are u an iit aspirant
In our education system, textbooks of lower standards creates confusion in view of teaching the students in a easy way ,but when at higher level we get to know the reality we are not even concerned to accept it, I thinks these types of misconception should be sorted at the first time to not crate any mess further
Great 👍👍
Such a beautiful explanation. Even a person who does not know the basics could easily understand this explanation. Thank you sir ❤❤
My physics teacher in school also taught us like that about the similar question.❤️
Hello sir ,
It would be really really great for all physics students if you take lectures completing the two volumes of “concepts of physics “ , it would be really helpful.
Sir as your books ( Two volumes ) are indispensable for all of us , your lectures will be !
Every student aspirant wether Neet or JEE has dream to learn from you ,
behalf of all students of India Sir do consider my humble request ..
Shalem .
Thats what makes you real practical physicist sir! You're awesome as always! 👏 From legendary book concepts of physics 1,2 to your video lectures. We all really miss you in IIT Kanpur campus! 😁 Still we love to brush our concepts from your lectures!
Lots of love and respect
Muba, geeky Engineer
I had the same question in my mind since i started studying current electricity but always ignored it. I found this video today and it was really helpful. Thank you so much sir. 🙏
I had the same doubt and i searched on TH-cam and thankfully your video came first now my doubt got clear thanks sir 🙏
I am surly agreed with your answer sir, sorry
But then what will be the use of resistor ?
What difference it will make in using it and not using it in a circuit ?
😃....
Total current will be reduced in the circuit if resistance is used..........👍
NOPE , BASICALLY RESISTOR IS A METAL AND METAL HAS SOME ELECTRONS IN IT , SO WHEN A BATTERY IS CONNECTED TO A RESISTOR IT CREATES POTENTIAL DIFFERENCE ACROSS THE RESISTOR AS A RESLUT ELECTRONS WHICH ARE NEGATIVELY CHARGED GET ATTRACTED TO POSITIVE TERMINAL OF BATTERY AND START MOVING TOWARDS THE + TERMINAL AND THIS MOVEMENT OF ELECTRONS RESULTS CURRENT
I am in btech 2nd year in electrical engineering
I got to know now
Thank you sir 👍🏻
Sir has very deep understanding about everything in physics and that's why he is HC Verma❤️❤️
Verma sir, you explain this question so wonderful.
Theoretically it can be said if current decrease in unit time then charge will also decrease in that time (because current is charge per unit time ) which opposes the law of conservation of charge . Hence current remains unchanged. Thanks
THE LEGEND OF PHYSICS.....Hatsoff
I have one stupid answer..🔥
(READ IT U'll BE Satisfied)
Many are saying one word answer as charge conservation.. this isn't true completely.
which means what charges are going in are coming out.
But current is the rate of flow of charge, the time taken by the charges to complete the journey in case of 0 resistance (no collision) will be lesser than with some resistance.
I=Q/t
=> I inversely proportional to time.
Since time taken is increased with adding up of resistance. Hence current (charge per unit time) will decrease.
Problem with what sir told is:
It should be even after resistance the amount of charge coming out is same as it's going in.. not the current which is time dependent.🙏🏻🙏🏻🙏🏻
my teacher insulted me infront of my class when i asked this question to her in class 8th
She didn't know , this is happen when they got job after doing ratta
9th me nhi hai electricity chapter
@@RahulKumar-qq6kd so may be in 8th , its been years now
@@genius9336 10th mai hai
@Daksh Dixit Bro there is chapter in 8 th namely 𝐂𝐡𝐞𝐦𝐢𝐜𝐚𝐥 𝐞𝐟𝐟𝐞𝐜𝐭 𝐨𝐟 𝐄𝐥𝐞𝐜𝐭𝐫𝐢𝐜 𝐂𝐮𝐫𝐫𝐞𝐧𝐭.
I am amazed by this video.in which a person answered for the question in every students mind with very simple and clear explanation.👍
we need teachers like hc verma sir to clear deep details necessary for research and development in india
Basically he explained it using the continuity equation, div(J) + d(rho)/dt=0. Nice.
#physicsconect
@@physicsconceptandeducation1949 c
Yes you right
Though I'm convinced with the logic given by sir but don't u think that there's some mistake occurred in the explanation of continuity equation....?? 🤔
Let me know if u think so...🤞
How does that equation hold in case of a capacitor?
If you're passing through a crowded place you'll be slow but that doesn't mean you'll lose weight.
But resiestance generates heat that is current is changed into heat so please explian
@@jdgoel4817 (I’m not professionally trained with electronics so this might be very wrong, it’s how I currently view this).
Keeping this analogy going; whenever you bump into someone or something you convert your movement into heat. You then start walking again, because you aren’t where you want to be and there is space somewhere else that just opened up. This doesn’t change that the amount of people going into the crowded place is always the same as the amount of people going out. As for where the energy for the heat comes from, that is from the pressure pushing the people in and the pressure pulling the people out. Because the person lost their kinetic energy bumping into something, it must (in a sense) “consume” some of the pressure to get moving again. Pressure is similar to the voltage difference between two places.
@@SethPentolope thanks
WORLD'S ALL STUDENT REQUIRES THE TEACHER LIKE YOU SIR , YOU'RE ARE JUST GREAT
The dislikes are those who studies from Pradeep only and attempted JEE Advance
Very funny🤣😝
Who Pradeep?
🤣🤣🤣
@@prakeernaghosh7924 it's a book
@@mohammedameenkhan2210 I guess this joke will forever be relatable lol
Asked this question in my school days to teacher and she just repeated the same line again without explaining ....now i got it after a couple of years.
very inspirational 🙏🏿🙏🏼👌🏼slay
yes very inspiring 👍🏽✌🏽
Slay indeed 🙀🙀🤝
He just taught 20 people 👴🏿☺🥶
Respected sir you have take my all the tension by answering this question
Thanks a lot
Well i am also a 10 grade student
Thanks dir
The current basically has no other place to go and therefore it will go through and come out of the resistance. To reduce the current within this setup, you will need to provide a different path for it to flow. Like connecting a parallel wire across the resistance, which can choose to include its own resistance. In that case, the current will split and more current will flow through the path of lesser resistance. Either way, when a current flows across a resistance, we loose voltage across it. And therefore, there is lesser voltage at the point where the current exits from the resistance in comparison to the point where it entered. This is because there was energy expended over the resistance.
Now suppose you have a current flowing through a resistance. And suppose you are able to gradually increase the resistance. You will observe that the current also decreases gradually. But whatever current came out of the battery in each instance will flow in and out of the resistance without change. In other words, the battery or voltage source will always decide to push out a current whose value is calculated by first internally _feeling_ the net resistance in the circuit before the current starts to flow. This internal calculation of nature is just ohm's law.
This means that if the initial resistance is very very high (imagine a rubber string instead of a copper wire), the voltage source will decide it cannot push a current through the circuit and no current will flow. If however, you now increase the voltage tremendously, there will come a point when it maybe possible to push a current even through this high resistance circuit.
But the main idea to understand is - whatever current the voltage source pushes out, after internally seeing the net resistance, it will flow through the loop and complete the circuit.
Best comment. HC sir is unable to explain here. If resistance doesn't oppose the flow of current, than why bulb lights up? The tungsten wire provide great resistance and in the process gets heated up. So here electric energy is being converted into heat and light energy by resistance.
What makes you think he didn't explain it well?
very nicely answered.. thank you
@@zainbunga3002 That's joule's law of heating (maybe the name is wrong , it's been a long time since I got across the topic)
@@zainbunga3002 thare samajh na aayo key
Drift velocity of electrons.Its the basics and given in school and college books but the thing is we never read to understand...we read to get pass with good numbers.
We read everything but we don't try to go deeply into anything and this is where we make faults.
Nice brief explanation by H.C VERMA SIR.
Textbooks should never say resistance opposes current....it leads to misconcepts
1)...resistance consumes energy(voltage×q passed)
2)...from where does this energy come?...from collision of electrons during moving under electric field....same energy which is provided by electric field(q×E×d) is lost in collisions...
3)That's why we have V(work done by field that accelerates unit charge in its journey)=iR(energy lost in collisions in resistance)..... You think yourself....all energy provided is lost in collisions.... that is why we have a constant value of i..{i=neavd..constant current means constant velocity and constant velocity means no net work has been done...i.e energy gained=energy lost}..
4)..resistance is basically dependent on the no. of times electron loses its energy in collisions during its journey...and has to accelerate again....this is from where R=rho L/A comes....if there was no resistance.... all electrons would never collide....no start stop journey....in a fraction, all together will reach low potential.... Giving rise to infinite current(short circuit).....similarly you can think of infinite resistance....journey of electrons never starts really...as they just keep colliding...
5)so the question was....why is current not decreased by resistance?....electron perform start(due to field)-stop(due to collision) motion through out the resistance.....if it decelerates due to collision... Then it also accelerates due to electric field....giving rise to a average value of current, which is same throughout the resistance.... More resistance means...it stops more often then it accelerates giving rise to a low value of current, but even then, it is uniform throughout the resistance.....i.e.overall value of current decreases...but not current itself........
6)many people also have doubt that V is work done per unit charge
While i×r accounts for total no of charges crossing × resistance....how can two things be equal.......one is concerned with single charge and one with all charges crossing!...... Ans is simple......i×r means neAvd×r.....i.e. it has both n and vd(drift velocity) terms in it....say n=1 and vd=2......then it signifies that wow vd is 2 of each electron.....hence good field must be acting on it....hence potential difference is good......now interchange and say n=2 and vd=1....hmm...vd is not high this time of this electron....but heyy!...it is also more crowded this time, thus vd=1 is also commendable here...there must be good potential applied. Which is true as 2×1=1×2....i.e potential is actually same in both cases....overall I conclude by saying....even though i×r includes 'no. of charge crossing term'....,but it has nothing to do with the no of charges crossing.... And only with the crowdness one unit charge feels while moving ......concluding that both potential and ir term are talking about 1 unit charge only....(one of energy gained, one of energy lost)..and hence can be equated to give us beautiful ohms law...which is nothing but a form of energy conservation!!!!...
Thankyou😊
Ps: Many people are saying...one word answer is charge conservation....why?...
By this explanation....cant charges lose their energy and stay in there afterwards?...i dont seem to get this explanation... resistance is not a pipe which will burst if more water is in it than volume...get me correct please...anyone?
Bhaia Hindi main samjha do .
Please 🥺
What does it mean when you say value of current decreases but not current
@@jyotiparihar5454 I think that he , want to say that when current pass through that circuit amount ( value of current) differ.
Waise mujhe bhi jyada samajh Nahi aaya.
Good morning @jyothi
Thats brilliant,thank you bro
@@imcharenbaatsongchanger7902 hi if you understand please tell me. In Hindi or in easy way.
The best teacher ever🥺oo godd the way he explains with such examples ❤️❤️
True the geniuses are always down to earth.... Respect to the proud of nation
The entire story in one simple line "It is not a tank here".
Resistance decreases rate of flow of current (di/dt), it does not decreases current (i)
Super
Wrong, resistance decrease rate of flow of charge(i.e. current). So it does decrease current.
@@MultiSpidyman 👍
@@MultiSpidyman You're right, provided the resistance is increasing.
Keeping the resistance constant, there wouldn't be any change in rate of flow of charge.
When resistance comes into picture, there some electric field associated with resistance which hinders path of incoming protons (or opposite flowing electrons) & hence there's some change in electric current.
The fact that HC Verma sir himself is explaining these questions, is a great privilege for current generation.
RIP Bernoulli's Equation
Equation of continuity
Av=constant
Half knowledge is dangerous
Cross section is same here
@@mainulmondal6183 but two different pipes
One of larger cross section area
And other lower
Av = constant
??
@@devamarwadi3612 we cant apply bernoulli's theorem for two different pipes
i think anology is wrong pipe with narrow area speed should be larger..
ac Bernoulli principles
Exactly. Speed increases in narrow pipes SO THAT the current doesn't change, that is the amount of electrons passing through the pipe per second.
Exactly.
@@kanyonful if the flow is smoth the speed of water will increase at narrower region. It will make sure same volume of water passes through every cross section whether large or small in a given time.
Yes.But sir NEVER said that speed is SAME in BOTH pipes.He has even used 'v1' for short pipes and 'v2' for larger pipe.The concept is speed whether v1 in small pipe or v2 in large pipe remains same in exit and entry.
Hope it helps!!
@@ssssaket
But sir says that v1 is higher then v2 how it possible (here V = velocity not volume )
Everyone -listening to his explaination
Me-Trying to find out if his spectacle frame has glasses or not
😂😂😂same
Same here😂🤣
lol😂
😀😂😂
You can see refraction of light on maxillary cheek bone
To ask doubts to teachers & pursue your query till getting answers is the very much key for students or everyone to learn. It's an real satisfaction. This is what I think.
Thank you so much sir... 🙏
But sir, according to the continuity rule, water will flow with a larger speed in a narrower pipe. av = constant.
Please clarify your explanation when you say that the speed will be smaller in a narrower tube. Water is incompressible as we know, from the same tap, it will flow swiftly in a narrow tube compared to that in a wider tube.
I also mentioned this after you, water-pipe analogy doesn't match
If the widths at any two points in the pipe are the same, the speeds of water at those two points will also be the same.
If you have a pipe whose width varies at different points, the speed of water in the pipe will vary accordingly. Smaller at wider points and larger at narrower points.
You are right and this is according to Bernoulli theorem
Yeah exactly that was my question too..
I too had the same question instantly
I wish i would have hc verma sir as my guru in physics when i was in college
see, you can't look at this concept in isolation, to understand let's take an example of simple circuit, 10 V battery, and 1-ohm resistor, according to ohms law, u will get 10 amp current from battery which will pass through 1 ohms resistor, now if u replace 1 ohms resistor with 2 ohms, according to ohms law u will get 5 amps current flowing through battery and resistor,
So, a resistor offers resistance to the overall circuit, and current of that circuit is based on that overall opposing force, but once resistor and driving force (here it is the battery) agrees to common current, it flows through the entire system.
now coming to, slowing down of charges, there is no point of slowing down of charges, as they already move very little, but it is the message of movement of charges which moves at almost the speed of light.
@@GhostsOfSparta It's so funny that you're contradicting your own statement!
@@ayan8233 corrected the comment I meant to say electrons flow.
@@GhostsOfSparta alright.
Yo election velocity is so lesser than speed of light..
@@parthasarathym1882 He means that the moment you complete the circuit, electricity starts flowing in it.
Thank you very much sir my 10th boards were coming I was so much confused but your analogy of water pipe helped me understanding it and I made my own analogy of something like air coming out of a balloon thing.
Ur name bro 😂
@@Hagrits_hat bhai ye I'd to dost KO chuna lgane ke liye bnai thi meri name toh alag hai
@@soldierboy69 yes bro pata tha real name nhi hai Relax 😂
Now next question is why does potential difference decrease after current flows through a resistance?
When you put a positive voltage on the ends of a resistor, electrons flow through it. The atoms in the atomic lattice of the resistor also move because of the temperature of the operating area. The moving atoms and electrons often bump together and the electron-flow gets slower, the potential energy(that´s why it's called potential) gets converted to heat. Voltage is just a potential difference.
That's also the reason why resistance changes with temperature and why resistors get hot when large currents flow through them.
so basically, a resistor offers resistance to the whole circuit and not just the part right before and right after the resistor, right?
Bhkkkk😂🤣🤣😂
In class10th
I also had a similar question that why current is same ,when it passes through different resistors connected in series.
the easiest & the most logically convincing concept explained in 3 minutes.. this the power of knowledge. when you know stuff beyond books
Greater the pipe diameter less the speed, smaller the diameter larger the speed of water. This is due to equation of continuity.plz sir correct the concept as the video is saying it opposite.
Exactly that is what i was thinking.. i think sir didn't mean to say that but somehow what is said is exactly the opposite.. no?
I think Here it means, smaller the diameter, greater will be the resistance because of increased collisions, and ultimately the flow will be resisted and slowed down.
@@learningwithtahira5920 But V2 will still be greater than V1 for the smaller pipe so it doesn't matter if the smaller pipe offered more chance of collisions
Yes thats how it should have been
I was thinking the same😅
90% people come to see his teaching style😍😍
Buy his books and spend 10% on reading and 90% on solving questions. I also did this mistake and I took so so much time just reading and analysing but it's not so deep meaning as much I thought so if you reading his books give more time in solving. 🙏😃
bhai gaming ke alawa padhai bhi krte ho mai bhi game delete kr diya kyuki mera iss baar 10th ka exam h
@@allthingisneeded7229 Maine poori 10th gaming kari thi lmao I was very lucky
Hey there Im ur subscriber 👌❤
I had this same question when i learnt about current and resistance! I couldn't find any explanation on any platform...but now i got it 🤩
Lot many comments in the comment section are speaking about this analogy being an untrue and non exact one.
Reasons being cited are "AS PER CONTINUITY EQUATION FLOW SHOULD BE MORE FAST IN NARROWER PIPE"
EXPLANATION:
If you ever study fluid mechanics in detail then you will come across equation called "DARCY WEISBACH EQUATION" H=flV^2/2gD... H is the head loss , V is the speed of fluid , D is the diameter of the pipe , f is the friction factor.
SO IF HEAD LOSS IS SAME (WHICH IS IN THE PRESENT CASE AS RESERVIOUR IS SAME IN BOTH CASES ) THE SPEED IS DIRECTLY PROPORTIONAL TO THE DIAMETER * D* OF THE PIPE . SO SPEED WILL BE LARGER IN LARGE DIAMETERED PIPE UNDOUBTEDLY!!.
.........................................
THEIR IS NO SCOPE FOR APPLYING CONTINUITY EQUATION OVER HERE AS THE PIPE CROSS SECTION REMAINS SAME IN BOTH CASES . THEIR IS NOTHING LIKE SMALL- BIG PIPE CONNECT IN PRESENT CASE ... SO DON'T THINK OF CONTINUITY ANY WAYS .
no brother...lets consider continuity equation flowrate what he tried to mean is that flowrate will be same in all crossesections of pipe.flowrate can be related to current here..speed cant be related to current.. Q=AV.. so when area of crossection decreases,velocity(speed) has to increase to keep flowrate same... the same when area increases velocity has to decrease inorder to keep flowrate same..the flowrate can be related to current not the speed..
Continuity equation can only be used if discharge remains const. For a pipe connected to a tap or something the discharge is variable. So continuity eqn can't be used. For small discharge, velocity will be less.
Sir, I'm Naveen Pandey the student of class 10th. Sir when we have the larger cross sectional area the velocity of water becomes decrease when water comes out from a tap or a pipe and when the cross-sectional area of the tap or pipe is small , the velocity of water increases. But sir when we turn on the tap a little, velocity of water from the tap is also little and when we open the tap completely, the velocity of water also increases why this happens?
Actually pressure effect the velocity ,and pressure depends upon area of cross section and Force
It can be easily explained by bernoulli’s theorem. Its a 11th class topic which you can read
You can understand by the equation of discharge
Q =AV
Where, Q= Discharge (flow) of water
A= cross sectional area of pipe
V= velocity of water
So, we can conclude that cross sectional area of pipe is inversely proportional to the velocity of the water
Uh can also say tht resistance is directly proportional to area of cross section so when the Area of Cross section is more thre will b more resistance nd decrease in velocity an when area of cross section is small thre will b less resistance and the velocity will increase
If uh agree reply plz...
❌Doubt ❌- Sir How nikola tesla conduct Electricity by air how?While air are insulator .please sir reply .i am highly Curious about it🙏
We can not say that air is insulator. Because electricity produced in rain which is of very high voltage is conducted by air. So air is a "BAD CONDUCTOR" of heat and not an insulator. That's the reason behind this.
Poor Conductor and insulator are 2 different things
MercuBLADE Air can conduct at low temperature and high pressure just as in the cathode ray tube experiment + it’s not an insulator
@@RameshKumar-xd1lm Wrong! Air is an insulator as well as a dielectric. Experiments prove that electric field tends to decrease in the presence of air. But,remains same in the presence of vaccum.
I think it happens due to magnetic field
Thank you sir..I had asked this question to my teacher many times but I cannot understand what he wants to explain but finally I got it why current does not decrease...thank you so much
Why it's difficult to understand?
It's a well known fact that current remains same in the entire loop of a circuit.
Current is how fast the charge travels, that is speed of charge travel.
For e.g: when current enters the resistor, 10 C passed every second, and when it left resistor 5 C passed a point every half second, so rate of transfer of charge remained same because charge density changed.
Before entrance less charge carriers (electrons, ions, etc) were travelling with high speed and at exit more charge carriers travelled with low speed (because of congestion), so total charge passing a point per second remained same.
Now I get it. I was comparing charge with speed instead of matter travelling at that speed all this time.
Make sure you understand the difference between current and charge.
You may feel the difference is arbitrary now, but if you want any degree with ECE, you'll do well to notice now that it isn't.
As much as i respect his teaching i have to say the explanation isn't completely accurate, the reason v1=v2 in the narrow pipe is because the pipe was always narrow from the start that is not the case with resistance, the resistance is offered somewhere in the middle.
Its still valid. Consider resistor as a large pipe connected to a narrow pipe connected which is connected to a large pipe . The velocity in first large pipe is v1 and the narrow pipe has velocity v2 on both ends then the velocitiy of the water comming from the last large pipe must be v1(i.e current going in=current going out)
@@abhijiths5237 you are right!
It's just an analogy my friend it's not 100% explaining what is happening but like I said it's an analogy meaning it's similar to that just not exactly the same
@@ElectroLight2876 yes
Lol as soon as the resistor is added it is in the same loop so it is a correct analogy,
Consider you can walk 500m in a minute in general, but you met a friend and you wasted a fraction amount of time in shaking hands(though not recommended at this time😂) and you were delayed by 10 sec, Right from 0m to 500m your friend can be anywhere in between and still can delay you for ten seconds.If you're going to meet a friend always than you will always be delayed!
What a lagend . i just joined this channel for this type of interesting question . lot of love for HC verma sir from pakistan 🇵🇰❤🇮🇳
If the pipe become narrower speed of water increases.
Ya if the amount of water is constant in both the pipes then water in narrow pipe will have greater speed, it means greater voltage with greater resistance and constant current, hence ohms law is proved🥳 R=V/I
Yaa bro you are right
@@varunds6328 Yes, but the speed at which the water from one side getting to the other side is lower in the narrower pipe right?
School And College Teachers Now a days should learn something from Internet
😁
Sir but we have studied in fluid mechanics that v is inversely proportional to a so in narrower pipe the speed should be more.
Exactly....that was my doubt too @H C VERMA sir
We are not talking bout fluid mechanics here ...it is not an anology so do not compare that with it ...he is just trying to explain resistance by this .
Yeah but he is 10th standard student and the motive was to explain him about current
@@sheelamishra2026 but he clearly mention that velocity will be less in narrower pipe.Maybe we are wrong at something,he should explain.
@@doctorcapacitor7932 it is only an analogy.
He knows about fluid mechanics more then anyone in this country.☺️
He would not meant what you understood.
The thing you are saying about fluid mechanics only works in laminar flow.
But in real life most of the fluids including that from a tap follows turbulent flow.
V is inversely proportional to the cross section only in laminar flow.
In turbulent flow, v is directly proportional to the cross section .
Same as in a thicker wire resistance is less while in a narrower wire resistance is high.
This is only an analogy.
I am also a student and not sure if we can define flow of current in terms of laminar flow or turbulent flow.
Btw, this a very nice question
Everyone had these type of doubts, but only few of them gets teacher like H.C. Verma, who give much deserving respect to the curiosity.