Class 10 Physics (India)
Let's learn what solenoids are, and why are they important. We will see that when we pass current through a solenoid, it produces a magnetic field similar to a bar magnet. Created by Mahesh Shenoy.
Want to join the conversation?
- Why does the field lines becomes straight at the center if the field lines always form concentric circles ?(7 votes)
- *the lines are nearly straight not expect but ya some what!*
*As the loops are so big that this small part nearly gives a straight line .*(5 votes)
- What all applications(in daily life) use variable magnetic fields?(3 votes)
- Would hard irons make magnetic fields stronger too or just soft irons?(2 votes)
- Hard irons when magnetized are very hard to demagnetize but soft iron can easily be magnetized or demagnetized easily. It depends on the number of turns of the solenoid or the current flowing through them. I hope this helps you :D.(2 votes)
- What are some examples of solenoids that we use in everyday life?(1 vote)
- how do we find the north and south pole in a solenoid?(1 vote)
- we know the magnetic field inside a bar magnet goes south to north. so if we find the direction of magnetic field inside a solenoid we will find which pole is north or south(2 votes)
- what are the sources of magnetism
- Well magnetic components create attraction which we find field lines created. Presence of field lines constitute magnetism(1 vote)
- Would a hard iron create a stronger magnetic field than a soft iron if taken in the same quantity?(1 vote)
- For creating a stronger magnetic field, you will have to increase the number of turns.
Generally, a hard iron differs from a soft iron only in the property that the former is harder to de-magnetize.(1 vote)
- What happens to a proton with a certain velocity if it were to travel through the axis of the solenoid?(1 vote)
in a previous video we saw that if you have an electric current carrying loop then it generates a magnetic field that's very similar to that of a bar magnet but it doesn't quite resemble a bar magnet because if you look inside the bar magnet over here then you can see that there is this long region where the magnetic field is pretty straight it's not exactly straight but pretty much straight and parallel to each other can you see that over here however if you look at our our artificial magnet over here then notice that the that this region where the magnetic field lines are straight is very short and so this resembles not a big bar magnet but a very tiny bar magnet so now the question is how do we create something that generates a magnetic field perfectly like a large bar magnet where we have a large region where the magnetic field lines are pretty straight inside that's what we should find out now so how do we do this well what if we bring in another current carrying coil over here so let's say we bring in another current carrying coil and place it down here somewhere then it's identical to this one so it's going to produce an identical magnetic field of its own and I'm going to show that in a different color over here but remember magnetic fields can never ever intersect and so the total magnetic field of these two coils together won't look like this because the atman here they're intersecting so you know what's gonna happen the two magnetic fields are going to merge together and he was a new magnetic field that's gonna look somewhat like this whoo look at the combined magnetic field we now have a straight region over here we also have a straight region over here but in between it's kind of bulky so how do we straighten this out well I'm pretty sure you can guess now let's add one more current carrying coil in between over here and let's see if it straightens out so if we introduce another current carrying coil again it's going to generate its own magnetic field which I have shown in another color and I'm pretty sure it's looking like a mess right now but again the magnetic fields don't ever intersect so now this magnetic field will merge with the previous magnetic field and together the magnetic field of all the three coils together it's gonna look somewhat like this hey you look at this magnetic field we are getting close to what we want but again we have these little bulging out regions we have little Moving's over here and I'm pretty sure you know what to do next well just keep adding more and more coils in between so you know what let's go crazy let's say we add 50 coils in between I'm not gonna show all the 50 coils and we also wanna show only few one but let's imagine we add something like 50 coils I'm pretty sure you can guess what's gonna happen the magnetic field inside is gonna become almost straight now and these regions are also going to straighten out and so the new magnetic field of all these coils together will look like this and tada we have done it this looks exactly like what we wanted so if we have lots and lots of current carrying coil then it resembles a bar magnet now of course to make this construction easier instead of taking different different loops and keeping it on top of each other we could take a single wire and then coil it like a spring to give us multiple loops somewhat like this see you have taken a wire you coil it multiple times and pass current through it and since you are getting a magnet due to electric current we call such magnets electro magnets in this particular electromagnet which has a shape like a pipe or a tube because of so many coils we hear the name it's called a solenoid and the word comes from German Solon which means pipe and Otis which means shape so whenever you coil something so much that it looks or resembles like a tube or a pipe we tend to call it a solenoid and when you pass current through it it behaves like a bar magnet and when one side of it acts like the North Pole and the other side acts like a South Pole and guess what electromagnets have great advantages over permanent magnets you see as the name suggests these have their magnetic fields permanently fixed you can't change them but in electromagnets if you increase the strength of the current you can increase the magnetic field strength if you switch off the current the magnetic field disappears and the electromagnet gets turned off if you reverse the direction of the current the magnetic field will reverse and as a result you can reverse the poles so it's very versatile in the sense you can control its magnetic field but the only the only disadvantage is that if you want to use it for a long time you have to continuously supply electric power to it it runs on electricity but if you have to use permanent magnet for a long time go ahead it's free of cost so depending upon what we want in some cases like in MRI machines in magnetic trains where we want to keep changing the magnetic field we're going to use electromagnets but in some cases where we don't want the magnetic field to change it makes me it makes perfect sense to use permanent magnets over there em lastly we can make electromagnets way stronger by introducing a soft iron rod you see ion is a magnetic material this means when you place it in a magnetic field it gets magnetized starts behaving like a magnet and adds on to the magnetic field already generated making it much stronger but soft ion the word soft here does not mean it's it's soft like a pillow softer hands are kind of ions that can be easily magnetized and when you switch off the current they will easily demagnetize they sort of like temporary magnets that's what we need over here for electromagnets right but there's another class of ion called hard ion these are the ones which are extremely hard to magnetize but once you magnetize them they're extremely hard to demagnetize as well these are the materials that we will use for making permanent magnets so what did we learn in this video we saw that if you take a wire and coil it many many times around to make a shape like a pipe we'll call it as a solenoid and when you pass current through it it generates magnetic field very similar to that of a bar magnet we call such material causes devices electromagnets and by introducing soft iron a kind of iron that can be easily magnetized and demagnetized we can enhance the magnetic field and make the electromagnets very stronger