# Electrical Engineering: Ch 14 Magnetic Coupling (22 of 55) Series Aiding vs Series Opposing Connect.

Welcome to electron line well at this point you may have started wondering how do you actually connect inductors in such a way that you have a dot on one side and then dot on the other side well it turns out it's pretty straight forward and here i wanted to give you that conceptual view.

Of what that looks like and we're going to do it by showing you the difference between what we call a series aiding versus a serious opposing connection a serious aiding well first of all series means that you put the two inductors in series one after the other on the same line.

And when you have them aiding that means that the dots will be on the same side of the inductor and the current will entered on the dot side for both inductors series opposing connection means that you put the dots on the other side so that in this case the current will enter on the dot side and here the current.

Will enter on the opposite side but what does it look like in real life well of course inductors are essentially wires that are wound around a core it could be it's a hollow core typically and notice here we're winding them like this where in the front you come up and then you go around the back come back up the front and so forth and so the.

Current will then flow around the coil like this and then here notice you do the same thing so you're winding the coil in the same direction in the front here upwards and then down on the back side up on the front down on the back so it's exactly the same for both coils now this is what we call a series aiding connection that means the dots on the.

Same side of the coil also notice that when you use your right hand rule and you point your fingers in the direction of the current your thumb will point in the direction of magnetic field so for coil 1 you have the magnetic field in this direction for coil 2 you have the magnetic field in the same direction now.

Some of this magnetic field will spill over so typically the magnetic field will go around like this and come back on the other side and so the magnetic field will come around like that but at the center it will go a little bit further before it starts curling over and then you can see that some of the magnetic.

Field will actually be aiding the other magnetic field over here which means that the mutual inductance increases the magnetic field in the other coil due to the present magnetic field in this coil and vice versa this magnetic field will extend out into this coil and there'll be some mutual interaction which is beneficial or.

Aiding in that respect aiding meaning that it will build up additional magnetic field in both coils due to the mutual coupling between the two coils and that's why we have this additional term that can store additional energy because you're actually increasing the flux the magnetic flux inside each.

Of the two coils and the total energy in the circle will then be increased by this term but what happens when you have them wound differently in this case you have the coil winding around like this and then here you have the coil one in the opposite direction so that the current will come up on the front side and down.

The back side here will come up on the back side and down on the front side so notice then if you use your right hand rule on this side the magnetic field will point to the left but on this side you have to turn your hand around and notice that now my thumb points to the right and notice that the magnetic field now points in the opposite direction so.

Any field of this coil that penetrates through this coil right here will now be in the opposite direction so it will actually diminish or reduce the magnitude of the magnetic field here and vice versa here the magnetic field will be reduced by the magnetic coupling between the two coils so when they're what they call in the.

Series opposing connection that means we have the dots on the opposite side the current enders on one side here and on the other side are essentially the winding is in the opposite direction and so that means you reduce the magnetic field in each of the coils which therefore reduces the total energy in the system by this amount because of.

That opposition to the existing magnetic fields in each of the coils caused by the current in each of the coils that hopefully will clarify first of all what that means what the dot symbol means it's simply a differential between how the coils around and how the current enters the coil on one side or on the.

Other side therefore creating magnetic fields either in the same direction or magnetic fields in the opposite direction and that is how that works