1. Introduction: The Magnet on the Fridge
You have seen a magnet stick to a steel almirah or the door of a fridge. You have felt it too — when you bring two magnets close, sometimes they jump together, and sometimes they push each other away, even before they touch.
That "before they touch" part is the strange bit. There is empty air between them. Nothing is connecting them that you can see. Yet a force is already acting.
So here is the real question. The magnet is sitting still on the table. The space around it looks empty. But a second magnet, or a small iron nail, feels a pull the moment it enters that space. What is filling that empty-looking space? And — this is the hard part — how do you draw something invisible so you can talk about it, predict it, and answer questions on it?
That is what this whole topic is about: making an invisible thing visible with a picture you can trust.
Stop scrolling. Try it in your head before reading on: when two magnets push apart with a gap of air between them, what is carrying that push across the gap?