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Current time:0:00Total duration:7:09

Video transcript

I have always been fascinated by magnets I can play with them for hours together the most curious question I always had about this is how does the magnetic force transmitted over a distance you don't need to touch it to push it I think that's what fascinates everyone about magnets right so how does the magnetic force work how does it travel over a distance does this magnet somehow know that there is another magnet out over there how does it how does it know is it a ver of its surrounding what's going on well here's how we like to think about it today we don't think that the magnets directly push and pull on each other instead we like to say that this magnet for example creates some kind of an influence around itself making its presence felt far away and it's because of that influence the second magnet gets affected so let me give an example the other day when I entered the house I immediately got a strong smell of jasmine now I don't like jasmine a lot but my wife loves to wear it so because of that fragrance I immediately could feel the presence of my wife somewhere in the house from a far away distance so you see what what the flowers had done the flower had created some kind of a fragrance all around the house making its presence felt and the moment I walked in my nose came in contact with that fragrance and I automatically experienced a smell in a similar manner we could think that this magnet for example is creating some kind of a magnetic fragrance all around it and when the second magnet comes in contact with that fragrance it automatically doesn't experience as well but it automatically experiences a force so this magnetic fragrance we give a technical name for it we call it the magnetic field so this magnet is generating a magnetic field around itself and when the second magnet comes in contact with the field it's getting pushed by that field and similarly even this magnet is generating its own magnetic field which I have not shown over here and that field is the one that's pushing and pulling on this magnet so it's the fields that push and pull on other magnets however there is a big difference between magnetic fields and the fragrance created by flowers you see what we call as fragrance is basically some molecules which are spread out by the flower which mix into the air and enters into my nostrils and creates a smell but over here the magnets are not spreading out any particles into the air there are no particles moving anywhere but still their magnetic field exists so that makes it a little bit more interesting and a little bit deep but we another question we could ask over here is if there are no real particles that we can detect then how do we know that this magnetic field is real that it really is present it exists how do we know that well here's how suppose I keep this magnet close to this magnet let me know that right now this matter is pushing this magnet away from it but what do you think would happen if I were to instantly make this magnet disappear you might expect the force on the magnet will also disappear right but careful studies careful experiments show us that the force does not immediately disappear it shows us that for a very very small fraction of a second that force still exists the force is not instantly disappear but it it lasts for a very small amount of time how do you explain this well again if we come back to our example let's say I go to my wife and then I take those jasmine flowers and throw it outside the window what do you think is going to happen well my wife is gonna be pretty mad at me but but besides that do you think the smell in the room in the fragrance in the room immediately vanishes no it doesn't right it's still it would still be present for some time even though that those flowers are gone its presence can still be felt for some time you may have experienced this similarly over here this magnet is producing its own magnetic field around it now when we make this magnet disappear its field doesn't instantly disappear it feels last for a very very small amount of time now that time is extremely small maybe fractions of a nanosecond something that we may not be able to detect in our experiments but it doesn't matter it does exist for a very small time and it's during that time this magnet can still feel the presence of the other magnet so the very fact that the force is still present for a very short time but it doesn't matter however short it may be it doesn't matter it existed for a short time even when this magnet was removed convinces us that magnetic fields are very real that they're there and the field concept is so incredible that we have now applied them even for other forces over a distance for example how do these charges pull and push each other over a distance well we can say the charges produce then influence around themselves making their presence felt this influence is called the electric field it's called electric field because it only affects electric charges and similarly even the force of gravity say between Earth and the moon acts over a distance how does it work well we say both the earth and the moon create a gravitational field and it's the gravitational field that pushes other objects which have masses gravitational fields affect masses electric fields effect electric charges and magnetic fields effect magnetic materials or magnets so to summarize how do magnets push and pull each other over a distance well they don't directly a magnet will create a magnetic field around it making its presence felt far away and when any other magnet comes in contact with that field it automatically experiences a force