11th Class Physics Chapter 10 | Magnetic Flux Linkage | 11th Class Physics New Book 2025

[00:00:06]Assalam awaikum dear student this is kaash madid your physics teacher student today our topic is magnetic flux linkage now student earlier you discussed magnetic flux talked about magnetic flux density we said that number of magnetic field lines passing through a unit area which you kept in the direction of magnetic field lines or you kept it perpendicular to the direction of magnetic field lines. Or inclined to the direction of magnetic field lines.

[00:00:34]We studied three different cases of his. Then we defined magnetic flux density. Ok? So in today's topic, you will see that magnetic flux linkage is linking with it.

[00:00:43]Now students, first let us understand what is magnetic flux linkage?

[00:00:48]Basically. Now [nasal sound] see if you have a solenoid basically. Ok? And that means you see there is a coil in it. Consider a coil and it has n number of loops. Ok? How many are there? There are n number of loops. For example, look at this, there is one loop, second loop, third loop. Now in every loop, this loop here is behaving as a vector area. There will be flux from this also. Suppose its flux is b. What flux also comes from this loop? b What flux do you have for this also?

[00:01:22]5B What is the flux of this also like this? 5B And what is the total number of loops you have? Four. So basically what we will do is that the flux of this through any loop will be multiplied by n number of loops. So what you have done is you have multiplied it with n number of loops. Flux through a Look, so many lines are passing here also. So much here, so much here.

[00:01:49]So what will we do? Number of loops we will know that it has 100 loops. It has 1000 loops or how many. Like in the case of transformer, we discuss that it has two coils, primary and secondary coil. His number of loops varies. So in this way we can easily calculate it using this concept of magnetic flux linkage.

[00:02:09]So flux you can say this. Then from this we make its formula. And we will also define that magnetic flux linkage refers to the product.

[00:02:18]What is this? Basically whose product is it? One, you have magnetic flux B and the other, what is it? Magnetic flux through a coil. We will especially talk about the coil, what do we make by binding the wire in it? Make the coil. And the product of the number of turns in the coil and its total number of turns will give the magnetic flux. So what should we call this product? Basically we will take magnetic flux and say it. So the product of magnetic flux through a coil and the number of turns in the coil. If you multiply the number of turns by the magnetic flux, what will you get? This is called magnetic flux linkage.

[00:02:57]Ok? Now students, in its explanation, make the same points which I have just explained that it measures how much magnetic flux is linked with the coil due to its multiple turns. How do the multiple turns of a coil affect its flux? Ok?

[00:03:13]So, I am again taking the example of transformer because we use this concept there also. After that, we will use this concept in Faraday's Law of Electromagnetic Induction also.

[00:03:23]Ok? This is how the electric motor works. Ok? There is a generator.

[00:03:28]You use this term in their cases also.

[00:03:30]Magnetic Flux Link. So this way we can tell how much magnetic flux is linked with a coil. Meaning there is a coil.

[00:03:38]How is Flux linking with his number of loops? If the number of loops is less then what value of flux will you get? It will come less. And similarly, if the number of loops is more, then what will be the overall magnetic flux that you will get? Value Greater. For example, you have four loops, so you multiply them by four. In this way, if there were six number of loops, you would multiply this flux by six and the value would increase.

[00:04:02]Ok? So here you can also explain this point.

[00:04:07]You have to look for these mathematically relation MCQs.

[00:04:09]This topic is only for your objective.

[00:04:11]Ok? Where b is the magnetic flux through a single loop of area a. So b is from a single loop. So we will multiply it with n number of loops.

[00:04:18]Then you will have flux. Because from here to here you have uniform magnetic field lines. Ok? The flux will remain the same.

[00:04:26]So we'll just condense the loops and multiply them. Out of a single loop that is flux. Now in this sense the same points which I have just discussed play a crucial role in the design and operation of transformer. If you want to design a transformer, you will consider the number of loops and look at the flux through one and so on because what do you get from the changing magnetic field line? The currents are reduced and that is what you have as alternating current which you use further and in the case of generators and electric motors you can talk about it. You can use the same concept in generators also. Ok? is an inductor. All of this will happen as you move further into electromagnetism.

[00:05:09]So you will see the working of all these, transformer, generator and inductor.

[00:05:14]Ok? So this concept is practical in Faraday's law of electromagnetic induction. So I have just told you this for MCQs that we will use this concept in Faraday of Electromagnetic Induction also. So simply for this short question you have to remember what is magnetic flux linkage? The product of the magnetic flux through a coil and the number of turns in the coil. Ok? So hopefully you must have understood it this way. See you in the next lecture, Inshallah. Allah Hafaz.

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