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So before I tell you what is electromagnetic induction, I would like to tell you about magnetic flux. because magnetic flux is a kind of prerequisite for electromagnetic induction. I mean you should know what is magnetic flux before we go ahead and study about electromagnetic induction because without having a very clear idea about magnetic flux it will be really difficult to understand the phenomenon of electromagnetic induction.
So let us look at it what is magnetic flux. However I have hinted you about magnetic flux when we were studying magnetism but here we will study it in little more detail so that your concepts are clear about flux. So magnetic flux is very analogous to what we study as electric flux and electrostatics. So what is electric flux? It is nothing but the number of electric lines of force which crosses a particular area.
So we call that as electric flux right. Similarly, when I talk about magnetic flux, I talk about the magnetic lines of force which crosses a particular area of an object, right? So, we define magnetic flux as the product of average magnetic field times the perpendicular area that it penetrates.
So the amount of magnetic field lines which crosses a particular area. So when I talk about magnetic flux I talk about the orientation of the area. The area which we are talking about in magnetic flux is not your scalar area. It is the area vector we are talking about and why we consider area vector. I have discussed it a couple of times in my previous videos that since the amount of flux, since the amount of lines crossing an area also varies with the orientation of the area.
That is why area is treated as a vector quantity. So we often call it as area vector. So how do we define magnetic flux mathematically?
We say that magnetic flux which we generally denote as phi b. or many a times we denote it only with phi. But when you have both electric to differentiate between electric flux and magnetic flux, we use the subscript phi E for electric flux and phi B for magnetic flux.
So when we talk about magnetic flux. We define it as B dot A where B is the magnetic field vector and A is the area vector. So we call it as B A cos theta. So what is theta?
Theta represents the angle between area vector and the area vector. and magnetic field right so what is this area vector what determines the area of determines the direction of area vector the normal to area vector right for example we will consider some scenarios let us suppose that we have a magnetic field in this direction right and we have an area like this so what is the value of theta in this case since this is the area so normal to area this this would be the normal vector to area so the direct so angle which this normal vector meets with the magnetic field is 90 degree so in this case theta is equal to 90 degree right so what would be the value of flux here since theta is 90 therefore flux will be equal to 0 similarly if we consider another scenario where we have magnetic field in this direction we have an area vector like this So what would be the value of theta here? First we draw the normal to the area vector. So this is the normal to the area vector.
So the angle which normal makes with the magnetic field is 0. So in this case theta is 0 and cos 0 is 1. So in this case the value of phi would be maximum that is b into a. Right. So I hope you understand how do we determine the orientation of magnetic field and area vector. Now some other properties of magnetic flux includes that it is a scalar quantity because it is nothing but measure of number of magnetic lines of force.
So it is a scalar quantity. The SI unit is Weber and amongst other units comes. Maxwell.
So when I talk about Weber, Weber is nothing but Weber is 1 Tesla into 1 meter square because Tesla is the SI unit of magnetic field and meter square is the SI unit of area. So we can say that 1 Weber is nothing but 1 Tesla into 1 meter square and the other unit that is the CGS unit is Maxwell. So how do we relate Maxwell and Weber? So we say that 1 Weber is equal to 10 to the power 8 Maxwell.
So, this is how we relate a Weber and a Maxwell. So, now let us now that we are aware of the concept of magnetic flux it is time that we can start with electromagnetic induction. Thank you. Please visit examfear.com to watch free educational videos, try free online tests, get the best quality study materials, study from the best tutors and mentors and much more. Thank you once again.